Upcoming protobuf 5 contains breaking changes, restrict to 4 for now.

[peterallenwebb]

Relates to #9566

Checklist

• I have read the contributing guide and understand what's expected of me
• I have signed the CLA
• I have run this code in development and it appears to resolve the stated issue
• I have opened an issue to add/update docs, or docs changes are not required/relevant for this PR
• I have run changie new to create a changelog entry

[github-actions]

Thank you for your pull request! We could not find a changelog entry for this change. For details on how to document a change, see the contributing guide.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 54.04%. Comparing base (9a1f20a) to head (6ffef7b).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #81   +/-   ##
=======================================
  Coverage   54.04%   54.04%           
=======================================
  Files          49       49           
  Lines        2866     2866           
=======================================
  Hits         1549     1549           
  Misses       1317     1317           

Flag	Coverage Δ
unit	54.04% <ø> (ø)

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