Automatically bump go patch version in main branch go.mod

[kaovilai]

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Please add a summary of your change

Add new action that creates PR to bump version of golang used based on golang version in container image.
https://go.dev/doc/toolchain introduced toolchain to go.mod and we wanted to avoid go mod tidy triggering adding this line.

This PR adds new action that creates PR to bump version of golang used based on golang version in container image and avoids main branch using older golang than release branch (ie. release-1.15 branch uses golang 1.22.8, when main is using older golang 1.22.0).

It is practically impossible to run go mod tidy with just go 1.22 as some user have requested. A patch version of golang always end up in a separate toolchain line which defeats the purpose of using generic 1.22.

At least with this PR, go.mod of main branch will be latest possible golang patch version.

We would expect upon merging that next day or upon manual trigger, a PR with go.mod updated to latest go patch matching container image is created.

See manual runs from this workflow here https://github.com/kaovilai/velero/actions/workflows/auto_bump_golang.yml

PRs created by this workflow: https://github.com/kaovilai/velero/pulls?q=is%3Apr+author%3Aapp%2Fgithub-actions+base%3Amain+head%3Aactions%2Fupdate-go-mod-patch+

This is similar to dependabot updating deps. However, dependabot do not currently updates golang version in go.mod.

Lookout for following log in this PR's action run.

go: upgraded go 1.22.0 => 1.22.9

Does your change fix a particular issue?

Fixes #(issue)

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• Accepted the DCO. Commits without the DCO will delay acceptance.
• Created a changelog file (make new-changelog) or comment /kind changelog-not-required on this PR.
• Updated the corresponding documentation in site/content/docs/main.

[kaovilai]

/kind changelog-not-required

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 58.96%. Comparing base (1fbd22f) to head (1e53458).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #8392   +/-   ##
=======================================
  Coverage   58.96%   58.96%           
=======================================
  Files         367      367           
  Lines       38895    38895           
=======================================
  Hits        22933    22933           
  Misses      14500    14500           
  Partials     1462     1462           

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[kaovilai]

The requirement of the user is more accurately represented by #8397 and this PR do not satisfy the requirement.