Migrate to mlugg/setup-zig

[goto-bus-stop]

I don't have the bandwidth to maintain this action and I'm not even an active Zig user :)

There is now a new action developed by a Zig team member.

In most configurations, you can just change goto-bus-stop/setup-zig@v2 to mlugg/setup-zig@v1:

-- uses: goto-bus-stop/setup-zig@v2
+- uses: mlugg/setup-zig@v1

Or with a Zig compiler version:

-- uses: goto-bus-stop/setup-zig@v2
+- uses: mlugg/setup-zig@v1
   with:
    version: 0.13.0

Consider upgrading to the new action, as it's in a much better place to anticipate and react to future Zig changes.