ci: push nightly images to dockerhub

[aldy505]

Nightly images should be pushed to DockerHub. This is the only repository that don't do that.

#skip-changelog

[aldy505]

oh symbolicator don't need changelog. that's cool.

[aldy505]

Heya @tobias-wilfert @Dav1dde (Burak is sick) can I get this merged ASAP? This seems to be the blocker for getsentry/self-hosted#3750

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.41%. Comparing base (5a85fd7) to head (56d116a).
Report is 329 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1716      +/-   ##
==========================================
- Coverage   76.09%   74.41%   -1.69%     
==========================================
  Files         101      111      +10     
  Lines       15262    17929    +2667     
==========================================
+ Hits        11613    13341    +1728     
- Misses       3649     4588     +939     

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