add shared-change-checker CI step

[matt-codecov]

should automatically post/update a comment on PRs that change the hash of our shared dependency for reviewers to take a quick glance at

example comment (which was updated automatically as its PR switched to different hashes for shared):

[codecov-notifications]

Codecov Report

All modified and coverable lines are covered by tests ✅

✅ All tests successful. No failed tests found.

@@           Coverage Diff           @@
##             main     #686   +/-   ##
=======================================
  Coverage   98.08%   98.08%           
=======================================
  Files         432      432           
  Lines       36717    36717           
=======================================
  Hits        36013    36013           
  Misses        704      704           

Flag	Coverage Δ
integration	98.08% <ø> (ø)
latest-uploader-overall	98.08% <ø> (ø)
unit	98.08% <ø> (ø)

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

Components	Coverage Δ
NonTestCode	95.97% <ø> (ø)
OutsideTasks	98.07% <ø> (ø)

[codecov-qa]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.08%. Comparing base (141df34) to head (08e950e).
Report is 1 commits behind head on main.

✅ All tests successful. No failed tests found.

@@           Coverage Diff           @@
##             main     #686   +/-   ##
=======================================
  Coverage   98.08%   98.08%           
=======================================
  Files         432      432           
  Lines       36717    36717           
=======================================
  Hits        36013    36013           
  Misses        704      704           

Flag	Coverage Δ
integration	98.08% <ø> (ø)
latest-uploader-overall	98.08% <ø> (ø)
unit	98.08% <ø> (ø)

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

Components	Coverage Δ
NonTestCode	95.97% <ø> (ø)
OutsideTasks	98.07% <ø> (ø)

[codecov-public-qa]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.08%. Comparing base (141df34) to head (08e950e).

✅ All tests successful. No failed tests found.

@@           Coverage Diff           @@
##             main     #686   +/-   ##
=======================================
  Coverage   98.08%   98.08%           
=======================================
  Files         432      432           
  Lines       36717    36717           
=======================================
  Hits        36013    36013           
  Misses        704      704           

Flag	Coverage Δ
integration	98.08% <ø> (ø)
latest-uploader-overall	98.08% <ø> (ø)
unit	98.08% <ø> (ø)

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

Components	Coverage Δ
NonTestCode	95.97% <ø> (ø)
OutsideTasks	98.07% <ø> (ø)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.12%. Comparing base (141df34) to head (08e950e).
Report is 1 commits behind head on main.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #686   +/-   ##
=======================================
  Coverage   98.12%   98.12%           
=======================================
  Files         474      474           
  Lines       38073    38073           
=======================================
  Hits        37359    37359           
  Misses        714      714           

Flag	Coverage Δ
integration	98.08% <ø> (ø)
latest-uploader-overall	98.08% <ø> (ø)
unit	98.08% <ø> (ø)

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

Components	Coverage Δ
NonTestCode	96.07% <ø> (ø)
OutsideTasks	98.07% <ø> (ø)

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