Go: auto-bump go version

[maxday]

In order to reduce maintenance effort (see: #1812), it would be great to see go version to be auto-bumped.

I think there are two sub tasks for this:

1. Remove hardcoded go-version in GitHub Actions worflows as it can lead to version mismatch, ie on main today:

   opentelemetry-lambda/.github/workflows/ci-collector.yml

   Line 27 in 3af180d

   go-version: '~1.21.9'

   and

   opentelemetry-lambda/.github/workflows/ci-python.yml

   Line 51 in 3af180d

   go-version: '^1.20.8'

2. Use a GitHub action to auto-bump go.mod go version. Unfortunately that's not yet supported by Dependabot (source: gomod does not update the go version that is defined in go.mod dependabot/dependabot-core#9057)

I will tackle both of these
Thanks!

[maxday]

1. Should be tackled by this: feat: remove hardcoded version of go in GitHub Actions workflows #1839

[maxday]

now that 1. is merged, #1848 has been opened to tacked 2.