Import ABC from collections.abc for Python 3.10 compatibility.

[tirkarthi]

Ref : python/cpython#23754

ABC aliases were removed from collections in favor of collections.abc

[ymollard]

LGTM, thank you.
Pypot hasn't be tested against 3.10 yet. If you see other elements, please let us know.

[tirkarthi]

I don't find any test failures in Python 3.10. Sample run as below :

(.env) ➜  pypot git:(master) ✗ python -V                              
Python 3.10.3
(.env) ➜  pypot git:(master) ✗ python -m unittest discover tests
Exception in thread Thread-1 (_wrapped_target):
Traceback (most recent call last):
  File "/usr/lib/python3.10/threading.py", line 1009, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.10/threading.py", line 946, in run
    self._target(*self._args, **self._kwargs)
  File "/root/checked_repos/pypot/pypot/utils/stoppablethread.py", line 124, in _wrapped_target
    self._setup()
  File "/root/checked_repos/pypot/tests/test_crashed_prim.py", line 8, in setup
    raise Exception("Sorry I didn't do it on purpose...")
Exception: Sorry I didn't do it on purpose...
.../root/checked_repos/pypot/.env/lib/python3.10/site-packages/tornado/ioloop.py:263: DeprecationWarning: There is no current event loop
  loop = asyncio.get_event_loop()
/root/checked_repos/pypot/.env/lib/python3.10/site-packages/tornado/platform/asyncio.py:326: DeprecationWarning: There is no current event loop
  self.old_asyncio = asyncio.get_event_loop()
/root/checked_repos/pypot/.env/lib/python3.10/site-packages/tornado/platform/asyncio.py:193: DeprecationWarning: There is no current event loop
  old_loop = asyncio.get_event_loop()
......WARNING:pypot.server.httpserver:The webserver port 8080 is already used. May be the HttpRobotServer is already running or another software is using this port.
/root/checked_repos/pypot/pypot/server/httpserver.py:1134: ResourceWarning: unclosed <socket.socket fd=15, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=6, laddr=('0.0.0.0', 0)>
  logger.warning(
ResourceWarning: Enable tracemalloc to get the object allocation traceback
..WARNING:tornado.access:400 POST /motors/m1/goto.json (127.0.0.1) 0.56ms
WARNING:tornado.access:400 POST /motors/m1/goto.json (127.0.0.1) 0.55ms
.WARNING:tornado.access:404 GET /motors/unknown_motor/registers/present_position/value.json (127.0.0.1) 0.42ms
WARNING:tornado.access:404 GET /motors/m1/registers/unknown_register/value.json (127.0.0.1) 0.41ms
WARNING:tornado.access:404 POST /motors/unknown_motor/registers/compliant/value.json (127.0.0.1) 0.49ms
WARNING:tornado.access:404 POST /motors/m1/registers/unknown_register/value.json (127.0.0.1) 0.57ms
WARNING:tornado.access:400 POST /motors/m1/registers/compliant/value.json (127.0.0.1) 0.59ms
.WARNING:tornado.access:404 GET /motors/registers/unknown_register/list.json (127.0.0.1) 0.46ms
..WARNING:tornado.access:400 POST /motors/goto.json (127.0.0.1) 0.46ms
WARNING:tornado.access:400 POST /motors/goto.json (127.0.0.1) 0.56ms
WARNING:tornado.access:400 POST /motors/goto.json (127.0.0.1) 0.49ms
.WARNING:tornado.access:404 GET /motors/unknown_alias/list.json (127.0.0.1) 0.38ms
.WARNING:tornado.access:404 GET /motors/unknown_motor/registers/list.json (127.0.0.1) 0.39ms
..WARNING:tornado.access:404 GET /primitives/unknown_primitive/pause.json (127.0.0.1) 0.39ms
.WARNING:tornado.access:404 GET /primitives/unknown_primitive/methods/list.json (127.0.0.1) 0.42ms
.WARNING:tornado.access:404 GET /primitives/unknown_primitive/properties/list.json (127.0.0.1) 0.40ms
...WARNING:tornado.access:400 POST /records/unit_test/play.json (127.0.0.1) 0.78ms
WARNING:tornado.access:400 POST /records/unit_test/play.json (127.0.0.1) 0.78ms
WARNING:tornado.access:404 POST /records/unit_test2/play.json (127.0.0.1) 0.88ms
.WARNING:tornado.access:400 POST /records/unit_test2/stop.json (127.0.0.1) 0.71ms
..WARNING:tornado.access:404 POST /records/unit_test2/save.json (127.0.0.1) 0.59ms
.WARNING:tornado.access:404 GET /records/unit_test2/value.json (127.0.0.1) 0.60ms
.WARNING:tornado.access:404 GET /primitives/unknown_primitive/resume.json (127.0.0.1) 0.50ms
..WARNING:tornado.access:404 GET /sensors/unknown_sensor/registers/unknown_register/value.json (127.0.0.1) 0.57ms
WARNING:tornado.access:404 POST /sensors/unknown_sensor/registers/unknown_register/value.json (127.0.0.1) 0.67ms
.WARNING:tornado.access:404 GET /sensors/unknown_sensor/registers/list.json (127.0.0.1) 0.54ms
..WARNING:tornado.access:404 GET /primitives/unknown_primitive/start.json (127.0.0.1) 0.50ms
.WARNING:tornado.access:404 GET /primitives/unknown_primitive/stop.json (127.0.0.1) 0.77ms
.WARNING:pypot.server.httpserver:The webserver port 8080 is already used. May be the HttpRobotServer is already running or another software is using this port.
/root/checked_repos/pypot/pypot/server/httpserver.py:1134: ResourceWarning: unclosed <socket.socket fd=23, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=6, laddr=('0.0.0.0', 0)>
  logger.warning(
ResourceWarning: Enable tracemalloc to get the object allocation traceback
.sss
----------------------------------------------------------------------
Ran 40 tests in 47.675s

OK (skipped=3)