fix: Clean up repository by removing unused files and references

[Vivkzz]

Hey! I'm working on issue #1354 to clean up some unused files in the repo.

I found a couple of things that could be cleaned up:

1. There's a tstore_test.sol sitting in the root dir that's not doing much. It's just a basic test for tstore/tload ops and isn't part of our main test suite. Plus, we already have this covered with the Cancun upgrade support. No need for test files in the root!

2. The .codeclimate.yml file isn't being used at all. Checked the CI pipeline, README, and package.yaml - nada. It's just sitting there with some basic hlint config that we're not using. The only mention of it was in CONTRIBUTING.md which was outdated.

3. Fixed CONTRIBUTING.md by removing that outdated CodeClimate reference. We're actually using GitHub Actions, HLint, and our standard Haskell compiler warnings for code quality checks.

These changes should make the repo a bit cleaner and prevent any confusion for other contributors. Let me know if you want me to tweak anything!

[CLAassistant]

All committers have signed the CLA.

[elopez]

Hi! Thanks for the contribution! As there's already another open PR addressing this #1357 and it's a bit more comprehensive than this one, I'll be closing this to avoid duplicating efforts.