fix: correct updatecli golang manifest to update go.mod

[dduportal]

This should lead to a successful update of #273 once merged.

As explained in #273 (comment), there is an issue with the current go.mod update process:

• The go.mod file expects a version without the patch (only major and minor) as per ref. https://golang.org/ref/mod#go-mod-file-go
• Ideally, changing the go version should be done with 2 go mod <..> commands:
  • go mod edit -go=
  • When the go version is changed in the go.mod file, then the command go mod tidy is needed because the internal format can change between minor version (this is the case here with 1.16 to 1.17). It might also update the go.sum.

This PR uses a shell resource as a "source", to update the go version of the go mod in a temp dir, and prints the content of the tidied resuting go.mod file.

Please note that this PR also enables the updatecli workflow for all PR/branches:

• The updatecli diff command is always executed (to ensure that it's not broken when there are configuration changes)
• The updatecli apply command is only executed on the main branch of course
  => The goal is to validate that the new shell script resource works as expected (for instance that it successfully installs golang when runing withing its image)