fix: "ModuleNotFoundError: No module named 'typing_extensions'"

[bhamail]

Our internal Jenkins CI build was seeing errors like the one below:

ERROR [0.000s]: jake.test.test_main (unittest.loader._FailedTest)
2021-06-28 14:04:01 GMT-04:00  ----------------------------------------------------------------------
2021-06-28 14:04:01 GMT-04:00  ImportError: Failed to import test module: jake.test.test_main
2021-06-28 14:04:01 GMT-04:00  Traceback (most recent call last):
2021-06-28 14:04:01 GMT-04:00    File "/usr/local/lib/python3.7/unittest/loader.py", line 436, in _find_test_path
2021-06-28 14:04:01 GMT-04:00      module = self._get_module_from_name(name)
2021-06-28 14:04:01 GMT-04:00    File "/usr/local/lib/python3.7/unittest/loader.py", line 377, in _get_module_from_name
2021-06-28 14:04:01 GMT-04:00      __import__(name)
2021-06-28 14:04:01 GMT-04:00    File "/home/jenkins/workspace/devex/Free Tools/Jake/jake-nightly/jake/test/test_main.py", line 22, in <module>
2021-06-28 14:04:01 GMT-04:00      from jake.__main__ import _show_summary
2021-06-28 14:04:01 GMT-04:00    File "/home/jenkins/workspace/devex/Free Tools/Jake/jake-nightly/jake/__main__.py", line 35, in <module>
2021-06-28 14:04:01 GMT-04:00      from .ossindex.ossindex import OssIndex
2021-06-28 14:04:01 GMT-04:00    File "/home/jenkins/workspace/devex/Free Tools/Jake/jake-nightly/jake/ossindex/ossindex.py", line 25, in <module>
2021-06-28 14:04:01 GMT-04:00      from tinydb import TinyDB, Query
2021-06-28 14:04:01 GMT-04:00    File "/home/jenkins/.local/lib/python3.7/site-packages/tinydb/__init__.py", line 27, in <module>
2021-06-28 14:04:01 GMT-04:00      from .queries import Query, where
2021-06-28 14:04:01 GMT-04:00    File "/home/jenkins/.local/lib/python3.7/site-packages/tinydb/queries.py", line 28, in <module>
2021-06-28 14:04:01 GMT-04:00      from typing_extensions import Protocol
2021-06-28 14:04:01 GMT-04:00  ModuleNotFoundError: No module named 'typing_extensions'

The internal CI build is using python 3.7.

Posting this PR in case any python gurus have a better solution.

FWIW, this changes make the internal CI build happy again.

cc @bhamail / @DarthHater