ci: move to Python 3.10 & improve workflow

[Pwuts]

Background

Workflow was updated but now runs twice. Also runs with Python 3.8 which is inconsistent with README (#2342). pull_request_target is both risky and unnecessary: CI will already run on push in the fork.

Changes

• Split build workflow into lint and test workflows
• Run all checks even if some fail
• Fix double PR runs
• Adopted #2343

~~Documentation~~

~~Test Plan~~

PR Quality Checklist

• [ ] My pull request is atomic and focuses on a single change.
• [ ] I have thoroughly tested my changes with multiple different prompts.
• [x] I have considered potential risks and mitigations for my changes.
• [x] I have documented my changes clearly and comprehensively.
• [x] I have not snuck in any "extra" small tweaks changes

[aperullo]

Related: https://github.com/Significant-Gravitas/Auto-GPT/pull/2267

[Androbin]

Don't forget to update .github/workflows/benchmark.yml and .devcontainer/Dockerfile, see #2107

[ntindle]

PR for #2424 pt 1: "shirt sizing" is ready pending this pull request being merged into master on Pwuts/Auto-GPT/tree/ci/shirt-sizing