Bump cryptography from 48.0.1 to 50.0.0 in Python SDK

[kennknowles]

Bump cryptography version pin to 50.0.0 across all Python container image requirements files, and update the upper bound in setup.py to <51.0.0.

---

Thank you for your contribution! Follow this checklist to help us incorporate your contribution quickly and easily:

• Mention the appropriate issue in your description (for example: addresses #123), if applicable. This will automatically add a link to the pull request in the issue. If you would like the issue to automatically close on merging the pull request, comment fixes #<ISSUE NUMBER> instead.
• Update CHANGES.md with noteworthy changes.
• If this contribution is large, please file an Apache Individual Contributor License Agreement.

See the Contributor Guide for more tips on how to make review process smoother.

To check the build health, please visit https://github.com/apache/beam/blob/master/.test-infra/BUILD_STATUS.md

GitHub Actions Tests Status (on master branch)

See CI.md for more information about GitHub Actions CI or the workflows README to see a list of phrases to trigger workflows.

[github-actions]

Assigning reviewers:

R: @damccorm for label python.

Note: If you would like to opt out of this review, comment assign to next reviewer.

Available commands:

• stop reviewer notifications - opt out of the automated review tooling
• remind me after tests pass - tag the comment author after tests pass
• waiting on author - shift the attention set back to the author (any comment or push by the author will return the attention set to the reviewers)

The PR bot will only process comments in the main thread (not review comments).

[kennknowles]

The change is kind of massive - maybe it makes sense to separate a generalized update without the version bump? Or, likely, it'll be nearly identical minus just the cryptography lines so note really smaller.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 58.82%. Comparing base (b57aaac) to head (cfc35b7).
⚠️ Report is 45 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #39756      +/-   ##
============================================
+ Coverage     55.96%   58.82%   +2.86%     
- Complexity     2272     7638    +5366     
============================================
  Files          1113     1663     +550     
  Lines        175101   216420   +41319     
  Branches       1458     6536    +5078     
============================================
+ Hits          97988   127311   +29323     
- Misses        74654    84398    +9744     
- Partials       2459     4711    +2252     

Flag	Coverage Δ
python	79.88% <ø> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[damccorm]

The change is kind of massive - maybe it makes sense to separate a generalized update without the version bump? Or, likely, it'll be nearly identical minus just the cryptography lines so note really smaller.

Yeah, I think we can take it as is. We regenerate these dependencies every release (usually right after the cut, so this is timely), and these bumps should be helpful. Really this is just giving us visibility into the cascading stream of dependency updates that happens automatically if you don't explicitly pin every dependency.