GH action cleanup + z3 version bump

[rsoeldner]

This PR updates the Z3 version and (tries to) unify them across builds.
The version differences wrt architecture are as follows.

OS	New Z3 Version	Old Z3 Version
Ubuntu 20.04	4.11.2	4.11.2
Ubuntu 22.04	4.12.2	4.12.2
OSX	4.12.2	4.8.10

Ubuntu 20.04 uses an old glibc version preventing the simple update to Z3 4.12.2.

Additionally, this PR removes the Windows related steps which are not used anymore.

PR checklist:

• Test coverage for the proposed changes
• PR description contains example output from repl interaction or a snippet from unit test output
• Documentation has been updated if new natives or FV properties have been added. To generate new documentation, issue cabal run tests. If they pass locally, docs are generated.
• Any changes that could be relevant to users have been recorded in the changelog
• In case of changes to the Pact trace output (pact -t), make sure pact-lsp is in sync.

Additionally, please justify why you should or should not do the following:

• Confirm replay/back compat
• Benchmark regressions
• (For Kadena engineers) Run integration-tests against a Chainweb built with this version of Pact

[emilypi]

Make sure this is documented in the README and ReadtheDocs (if applicable). We should mention the minimum version bounds in any setup instructions for Pact.