use "go-version-file" for actions/setup-go

[majewsky]

@kayrus pointed out this setting in sapcc/maintenance-controller#369 (comment), and its specification sounds like what we want. This would be a nice way to reduce some noise in the git log because we don't have to change version strings all the time when new Go versions are released.

[github-actions]

Merging this branch will not change overall coverage

Impacted Packages	Coverage Δ	🤖
github.com/sapcc/go-makefile-maker/internal/ghworkflow	0.00% (ø)

---

Coverage by file

Changed files (no unit tests)

Changed File	Coverage Δ	Total	Covered	Missed	🤖
github.com/sapcc/go-makefile-maker/internal/ghworkflow/utils.go	0.00% (ø)	0	0	0

Please note that the "Total", "Covered", and "Missed" counts above refer to code statements instead of lines of code. The value in brackets refers to the test coverage of that file in the old version of the code.

[SchwarzM]

lgtm

[majewsky]

FYI, I will discuss this with Sandro on Monday. He has voiced reservations. Please do not merge until then.

[majewsky]

The concern that Sandro raises (summarizing from a DM thread) is that, if go.mod has e.g. go 1.25.0 instead of go 1.25 (which is not all that uncommon), then it will stay pinned on Go 1.25.0. For running tests, this is not a big deal, but in repos where we use govulncheck, it will scream about vulnerabilities in std that were fixed in Go 1.25.x for x > 0.

Also, there may be concerns about caching of action outputs that would cause runs to get stuck on old Go versions even if it could theoretically choose a newer bugfix version, were it not for the caching.

[kayrus]

@majewsky for me the go mod tidy behavior looks like magic. sometimes it modifies the go.mod file with go 1.25.0, sometimes with go 1.25, sometimes with toolchain 1.25.XX. I tried it with similar open-source projects and the result was different. I still don't know the pattern.

[SuperSandro2000]

toolchain was removed in a release a few months ago, it should no longer does that.

I think we get 1.25.0 if any dep is using that unless we are one minor version higher. If any dep is using 1.25.1 we get at least that.