ci: automatically create github release on tag

[skl]

This PR creates a new GitHub actions workflow that triggers when a git tag following the pattern v*.*.* is pushed to this repo:

• Automatically publishes a GitHub release
• Uses GitHub's auto-generated release notes
• The release is named the same as the git tag (follows current convention in this repo)

NOTE: publish_dockerhub_main.yml and publish_dockerhub_k8s_cache_main.yml also currently trigger on this same tag pattern push, I thought best to solve the ordering/workflow-calling in a separate PR.

In future, it would be possible to modify this workflow to handle e.g. artifact signing, uploading, and attaching to releases.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 46.26%. Comparing base (8b80320) to head (6fc7f54).

❗ There is a different number of reports uploaded between BASE (8b80320) and HEAD (6fc7f54). Click for more details.

HEAD has 37 uploads less than BASE

Flag	BASE (8b80320)	HEAD (6fc7f54)
oats-test	5	0
k8s-integration-test	15	0
integration-test-arm	1	0
integration-test	10	0
integration-test-vm-${ARCH}-${KERNEL_VERSION}	6	0

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #869      +/-   ##
==========================================
- Coverage   55.16%   46.26%   -8.90%     
==========================================
  Files         251      251              
  Lines       21481    21481              
==========================================
- Hits        11849     9938    -1911     
- Misses       8817    10901    +2084     
+ Partials      815      642     -173     

Flag	Coverage Δ
integration-test	?
integration-test-arm	?
integration-test-vm-${ARCH}-${KERNEL_VERSION}	?
k8s-integration-test	?
oats-test	?
unittests	46.26% <ø> (-0.01%)	⬇️

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