chore: update CONTRIBUTING.md and add pull_request_template.md #1238

Job	Run time
Run tests (Ubuntu, 3.8)	1m 48s
Check coding standards	34s
Run tests (Ubuntu, 3.9)	1m 45s
Run tests (Ubuntu, 3.10)	1m 48s
Run tests (Ubuntu, 3.11)	1m 45s
Run tests (Ubuntu, 3.12)	1m 47s
Run tests (MacOS, 3.8)	3m 44s
Run tests (MacOS, 3.9)	1m 26s
Run tests (MacOS, 3.10)	1m 38s
Run tests (MacOS, 3.11)	2m 8s
Run tests (MacOS, 3.12)	1m 22s
Run tests (Windows, 3.9)	2m 46s
Run tests (Windows, 3.10)	3m 20s
Run tests (Windows, 3.11)	3m 18s
Run tests (Windows, 3.12)	3m 6s
Build distribution	12s
Upload release to PyPI	0s
Sign the Python 🐍 distribution 📦 with Sigstore and upload them to GitHub Release	0s
Upload homebrew formula	0s
	32m 27s

Provide feedback