Update to go 1.18

[laurentsenta]

Closes #193

Todo:

• Sync with open PRs sequentially but continue updating branches in parallel #261
• Look into the "change our upgrade logic" discussed in issue 193 and add a note in the yml.

[marten-seemann]

I realize this is a PR targeting next, so this doesn't need to go into this PR. Just wanted to raise that we probably also want to update staticcheck (and check if there'll be a new release for Go 1.18) before running the deployment to all repos.

[galargh]

I accidentally created a duplicate of this in #308.

Reposting the comment from @mvdan on staticcheck:

I don't think we need to block adding Go 1.18 until the next staticcheck version is out. The main reason that staticcheck is broken with 1.18 is due to generics, but the vast majority of repos using unified CI will keep on supporting Go 1.17, meaning they generally can't use generics yet, unless they go for some funky business with //go:build go1.18.

This assumes that it will be painless to update staticcheck in a week's time once they do release proper support for Go 1.18, though. I assume that for most repos it would be a bit bothersome to merge the update to Go 1.18 this week, and a staticcheck update next week. For that reason, it might be best to wait a week until we deploy the Go 1.18 update.

Here's the staticcheck issue that track new version release progress: dominikh/go-tools#1166

Reposting the comment from me on next major unified CI release:

I'd really appreciate if we could do the next major unified CI release with #261 because it'd give us a chance that the release process itself succeeds without human intervention.

Reposting the section on testing I did with the exact same test set:

Updated .github-test-target in protocol/.github-test-target#37 (this also showcases the staticcheck issue)

[galargh]

I agree with Daniel on staticcheck, it'd be less noisy to wait for a week for that new staticcheck version.

And with Marten as well, we don't have to wait with merging this PR until staticcheck business is sorted out.