ci: Keep 50 package versions.

[jaqx0r]

If we build once a week then this gives about a year of pinning before people
have to upgrade. Personally I think 90 days should be the limit but I can't be
too prescriptive.

Fixes: #121

[github-actions]

Unit Test Results

    1 files     27 suites   8m 43s ⏱️
  672 tests   670 ✅ 2 💤 0 ❌
1 989 runs  1 983 ✅ 6 💤 0 ❌

Results for commit 8fac39a.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 0.00%. Comparing base (4dfa8e0) to head (8fac39a).
Report is 2 commits behind head on main.

Additional details and impacted files

@@     Coverage Diff     @@
##   main   #128   +/-   ##
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