build: remove experimental Python 3 tests

These tests do not help us to get closer to Python 3 compatibility and
they take up valuable time yet they always fail.

PR-URL: #29413
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Beth Griggs <Bethany.Griggs@uk.ibm.com>

.travis.yml

@@ -87,31 +87,3 @@ jobs:
         - if [ "${TRAVIS_PULL_REQUEST}" != "false" ]; then
             bash -x tools/lint-pr-commit-message.sh ${TRAVIS_PULL_REQUEST};
           fi
-
-    - name: "Python 3 is EXPERIMENTAL (Py36)"
-      language: node_js
-      node_js: "node"
-      install:
-        - pyenv global 3.6.7
-        - python3.6 -m pip install --upgrade pip
-        - make lint-py-build
-      script:
-        - NODE=$(which node) make lint lint-py
-        - python3.6 ./configure.py
-        - NODE=$(which node) make test
-
-    - name: "Python 3 is EXPERIMENTAL (Py37)"
-      language: node_js
-      node_js: "node"
-      install:
-        - pyenv global 3.7.1
-        - python3.7 -m pip install --upgrade pip
-        - make lint-py-build
-      script:
-        - NODE=$(which node) make lint lint-py
-        - python3.7 ./configure.py
-        - NODE=$(which node) make test
-
-  allow_failures:
-    - name: "Python 3 is EXPERIMENTAL (Py36)"
-    - name: "Python 3 is EXPERIMENTAL (Py37)"