chore: auto tagging after release pr is merged

[JaydipGabani]

What this PR does / why we need it: Eliminate the need for manually pushing tag to kick off release

Which issue(s) this PR fixes (optional, using fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when the PR gets merged):
Fixes #3037

Special notes for your reviewer:
Here is the workflow running on test fork
Here is the tag created as a result of the workflow

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (2370c50) 53.81% compared to head (1ef82ab) 53.72%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3135      +/-   ##
==========================================
- Coverage   53.81%   53.72%   -0.10%     
==========================================
  Files         136      136              
  Lines       12198    12198              
==========================================
- Hits         6564     6553      -11     
- Misses       5134     5142       +8     
- Partials      500      503       +3     

Flag	Coverage Δ
unittests	53.72% <ø> (-0.10%)	⬇️

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[JaydipGabani]

@maxsmythe Found a way to gate logic without comparing commit message. PTAL

[maxsmythe]

Nice! Who has permissions to create PR labels?

[JaydipGabani]

@maxsmythe anyone with write access to gatekeeper repo can edit labels and anyone with triage access can apply labels.

[ritazh]

LGTM

[sozercan]

LGTM

[JaydipGabani]

@maxsmythe do you have any additional questions/concerns?

[maxsmythe]

One last thought: are there more specific tests than "contains"? Seems like "startswith" or similar would be good for the PR title, and an exact match for the label.

[maxsmythe]

Though maybe the label check is doing an exact match?

[JaydipGabani]

Though maybe the label check is doing an exact match?

Yip, it is matching release-pr against all labels

[JaydipGabani]

One last thought: are there more specific tests than "contains"? Seems like "startswith" or similar would be good for the PR title, and an exact match for the label.

@maxsmythe updated to use startsWith from contains

[maxsmythe]

LGTM! Thanks for this!