fix: auto signing PR for dco

[JaydipGabani]

What this PR does / why we need it: Sign off PRs raised by release pr action to eliminate the need of manually signing it for DCO.

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 #3036

Special notes for your reviewer:

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (3a83700) 52.70% compared to head (7f9287a) 52.53%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3120      +/-   ##
==========================================
- Coverage   52.70%   52.53%   -0.18%     
==========================================
  Files         134      134              
  Lines       11890    11890              
==========================================
- Hits         6267     6246      -21     
- Misses       5138     5153      +15     
- Partials      485      491       +6     

Flag	Coverage Δ
unittests	52.53% <ø> (-0.18%)	⬇️

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see 3 files with indirect coverage changes

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[maxsmythe]

LGTM

[sozercan]

@JaydipGabani this is awesome! were you able to test this in your fork?

[sozercan]

LGTM pending testing confirmation

[JaydipGabani]

@sozercan Yes! I was able to test this on my fork. I don't have DCO rule set, but PR raised by the action has signoff msg attached to the commit. This is the commit done by the action.