[Feature] [GitHub-related] introduce GH Action checks for this repo  #11

Problem

current issue: lack of GH action that'd run fmt and lint on the PRs made
that'd be the minimum, that'd come in more than handy during further development of this project

Solution

similar gh actions were used in Coldfire, but given they're most likely outdated/not maintained anymore, Coldfire has the following issue - redcode-labs/Coldfire#41

the perfect solution would be to find some actions which are at least regularly maintained

Additional context

No response