Refactoring typing_inspect.py

Description

Previously, typing_inspect.py had a distinction between python versions <3.7 and >=3.7, and would change imports and return statements based on the python version. This refactoring changes this so that there are no longer special cases for python versions <3.7.

Fixes # https://github.com/Azure/azure-functions-pyfx-planning/issues/177

PR information

[ ] The title of the PR is clear and informative.
[ ] There are a small number of commits, each of which has an informative message. This means that previously merged commits do not appear in the history of the PR. For information on cleaning up the commits in your pull request, see this page.
[ ] If applicable, the PR references the bug/issue that it fixes in the description.
[ ] New Unit tests were added for the changes made and CI is passing.

Quality of Code and Contribution Guidelines

[ ] I have read the contribution guidelines.

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 85.44%. Comparing base (8f1c7b1) to head (13e4e04).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #1435 +/- ## ======================================= Coverage 85.44% 85.44% ======================================= Files 35 35 Lines 1965 1965 Branches 370 370 ======================================= Hits 1679 1679 Misses 213 213 Partials 73 73 ``` | [Flag](https://app.codecov.io/gh/Azure/azure-functions-python-worker/pull/1435/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Azure) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/Azure/azure-functions-python-worker/pull/1435/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Azure) | `85.39% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Azure#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

Azure / azure-functions-python-worker