fix: gha setup go cache issue [#1319]

[tinaboyce]

While looking at the GitHub Action runner executing a job, I have noticed an error during the "Set up Go 1.x" stage

Warning: Restore cache failed: Dependencies file is not found in /home/runner/work/saml2aws/saml2aws. Supported file pattern: go.sum

A quick look at the documentation and it had the actions/checkout before the actions/setup-go, while we had it afterwards, which probably explains why it cannot find go.sum.

Also (the bit that was outside the scope of the initial issue but I wanted to save multiple PRs):

• we are still using Go version 1.20 somewhere and after a quick search, I've came across a way to derive version from go.mod (https://github.com/actions/setup-go?tab=readme-ov-file#getting-go-version-from-the-gomod-file)
• ran the yaml file against a formatter, so there will be some formatting magic going on
• goreleaser wants actions/checkout to have "fetch-depth" of 0 for the changelog to work correctly for the gorelease release, as mentioned in the "IMPORTANT" section beneath the Workflow code block: https://github.com/goreleaser/goreleaser-action?tab=readme-ov-file#workflow

I am more than happy to move the "also" bit to a new PR if that is more ideal?

Closes #1319

[codecov-commenter]

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 42.19%. Comparing base (99d6fe4) to head (36c8b29).
Report is 50 commits behind head on master.

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Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1320   +/-   ##
=======================================
  Coverage   42.19%   42.19%           
=======================================
  Files          54       54           
  Lines        6456     6456           
=======================================
  Hits         2724     2724           
  Misses       3283     3283           
  Partials      449      449           

Flag	Coverage Δ
unittests	42.19% <ø> (ø)

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[mapkon]

I still prefer formatting changes to be separate from material changes.