Update main workflow with several changes

[h7x4]

The pipeline has been updated with the following changes:

• Run all steps in parallell
• Update several of the steps, also the entirety of actions-rs seems to be unmaintained
• Only run coveralls on PRs, to avoid breaking workflows on forks
• Add dependency cache to speed up the builds.
• Remove the benchmarking step, we have no benchmarks

We're still using action-rs/grcov which might break at some point as it's using deprecated API functions. I haven't found any good alternatives for this yet. But I think this should at least make less things break whenever the API gets deprecated for good.

[coveralls]

Pull Request Test Coverage Report for Build 6049149731

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-24.1%) to 41.79%

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Totals
Change from base Build 5988722268:	-24.1%
Covered Lines:	1527
Relevant Lines:	3654

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💛 - Coveralls