kvlist: make lookups case-insensitive

[patrick-stephens]

Resolves fluent/fluent-bit#9743 by making lookups case-insensitive.

Potentially also resolves fluent/fluent-bit#9537

Fixes up out-of-date workflow usage of old actions and versions too in #56 then merged in.

[braydonk]

I wasn't aware my approval would trigger the auto-merge, my mistake. Hopefully that's okay, it looks right to me.

[patrick-stephens]

Yeah I'll add some required checks and codeowners to ensure we sort that but I'd checked the CI was ok before automerge enabling

[patrick-stephens]

#57 adds the relevant changes and I've updated branch protection to ensure we have a required check now.

[edsiper]

While this resolves the high-level issue in Fluent Bit, I would not agree to get this merged into the underlying library, which pretty much needs to be agnostic for the user case of the "end-user" (Fluent Bit in this case), e.g: kvlist purpose is not only to serve the Fluent Bit config reader, many other components and peer libraries, this change adds a restriction/limitation: if we wanted to extend the lookup with a hashing mechanism case-insensitive becomes a restriction (unless the original key is stored in lowercase so the hash will match). Please do not rush the merge of PRs that are in active discussion, as well the history of the PR (commits) has a couple of duplicates, we want to avoid that.

I agree with the solution proposed in #58 which is sustainable.