Switch to Python 3 for pre-commit

[lboue]

Switch to Python 3 for pre-commit to make it work with Ubuntu. Otherwise:

user@Matter:~/Documents/ESP32_Display_Panel$ pre-commit run --all-files
astyle formatter.........................................................Passed
Check copyright notices..................................................Passed
flake8...................................................................Passed
trim trailing whitespace.................................................Passed
fix end of files.........................................................Passed
check for merge conflicts................................................Passed
mixed line ending........................................................Passed
Update when configuration files change...................................Failed
- hook id: sync-conf-files
- exit code: 1

Executable `python` not found

Update when versions change..............................................Failed
- hook id: check-file-versions
- exit code: 1

Executable `python` not found

[Lzw655]

Hi @lboue, thank you for the contribution. Let's merge it!