ci: fix ghcr push

[sozercan]

What this PR does / why we need it:
fixes ghcr image push since DH and GH org names are slightly different (openpolicyagent vs open-policy-agent)

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 #3697

Special notes for your reviewer:

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 47.69%. Comparing base (3350319) to head (6671713).
Report is 193 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (3350319) and HEAD (6671713). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (3350319)	HEAD (6671713)
unittests	2	1

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3698      +/-   ##
==========================================
- Coverage   54.49%   47.69%   -6.81%     
==========================================
  Files         134      236     +102     
  Lines       12329    19846    +7517     
==========================================
+ Hits         6719     9466    +2747     
- Misses       5116     9488    +4372     
- Partials      494      892     +398     

Flag	Coverage Δ
unittests	47.69% <ø> (-6.81%)	⬇️

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