Check sources PR GitHub Action failing to setup envtest

[AObuchow]

The Check Sources PR Action is currently failing as setup-envtest has upgraded to go 1.22. We are using the latest version of envtest to run our test suite, but using go 1.20.10 for our GH Action, which creates an incompatibility.

Ideally, the version of Go used in the project should be bumped to 1.22 but the golang 1.22 package for Fedora is only coming with Fedora 40, which releases April 16th 2024.

For the time being, we should pin the version of setup-envtest used to the latest version that uses go <=1.21.