Automatically create release tags via GitHub actions

[tautschnig]

The action is currently marked as DRY_RUN: true to perform testing, and
will be enabled in a subsequent PR. Edit: I have performed testing in my fork (see https://github.com/tautschnig/cbmc/runs/1533820084), and am thus inclined to immediately enable this over here.

• Each commit message has a non-empty body, explaining why the change was made.
• Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• n/a The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• n/a My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• n/a White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[codecov]

Codecov Report

Merging #5649 (5ad6803) into develop (fd8af8a) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #5649   +/-   ##
========================================
  Coverage    69.44%   69.44%           
========================================
  Files         1243     1243           
  Lines       100612   100612           
========================================
  Hits         69875    69875           
  Misses       30737    30737           

Flag	Coverage Δ
cproversmt2	43.14% <ø> (ø)
regression	66.34% <ø> (ø)
unit	32.28% <ø> (ø)

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[hannes-steffenhagen-diffblue]

Have you checked if the default GITHUB_TOKEN has the rights to create a tag? It not being allowed to do some things is something that has bitten me in the past, that's why I’m asking.

[tautschnig]

Good call out. I don't know whether this works, but also I'm not sure how to figure it out other than trying it out? (It seems safe to do so: in the worst case, it does not create a tag, and we'd have to go back to the previous, manual approach.)

[piotr-grabalski]

Does this read the latest version from the existing tags?
If not we may need INITIAL_VERSION too:

INITIAL_VERSION (optional) - Set initial version before bump. Default 0.0.0.

Probably something like: INITIAL_VERSION: 5.20.1?

[tautschnig]

Supposedly the bash script behind this GitHub action does check for existing tags. But it may be worth flipping DRY_RUN back on to make sure this does actually work as expected.

[tautschnig]

I have now added a commit to keep in in DRY_RUN mode.

[tautschnig]

A further comment: we should likely wait for anothrNick/github-tag-action#95 to be merged to maintain the cbmc- prefix.

[NlightNFotis]

Hi Michael, I'd love to get this in and experiment with this a bit - it would save us quite a bit of time!

Are you happy to take this forward (rebase on develop) or if you don't have the bandwidth for this, are you happy with me taking this over?*

*: (I'll close this PR and make a new one, but cherry-pick your commits on top of the new branch, and any changes by me will go in another commit, so your authorship is going to be preserved)

[tautschnig]

Closing: automatic tagging won't save much time as the tag can be produced at the same time as publishing the changelog.