Update flatpickr to the latest version 🚀 (carbon-design-system#535)

* fix(package): update flatpickr to version 4.2.4

* chore(package): update lockfile

https://npm.im/greenkeeper-lockfile

package.json

@@ -110,7 +110,7 @@
   "dependencies": {
     "classnames": "2.2.5",
     "downshift": "^1.23.2",
-    "flatpickr": "4.2.2",
+    "flatpickr": "4.2.4",
     "lodash.debounce": "^4.0.8",
     "lodash.isequal": "^4.5.0",
     "warning": "3.0.0",

yarn.lock

@@ -4329,9 +4329,9 @@ flatpickr@2.6.3:
   version "2.6.3"
   resolved "https://registry.yarnpkg.com/flatpickr/-/flatpickr-2.6.3.tgz#457357532deb135f3da64b425bf4435737961564"
 
-flatpickr@4.2.2:
-  version "4.2.2"
-  resolved "https://registry.yarnpkg.com/flatpickr/-/flatpickr-4.2.2.tgz#6f71310c2416a2291ec267bec4f33f321711453f"
+flatpickr@4.2.4:
+  version "4.2.4"
+  resolved "https://registry.yarnpkg.com/flatpickr/-/flatpickr-4.2.4.tgz#abd6dedd0fa41e2118acb96a22f49819ba2d0157"
 
 flatten@^1.0.2:
   version "1.0.2"