[OTHER] Adopt repo-review for tephi

[ESadek-MO]

❓ Other

Adopt and align tephi with repo review, as in cf-units.

### Tasks
- [x] Adopt repo review, with all checks ignored for the time being (#164)
- [x] Decide which standards should be maintained for tephi ([below](https://github.com/SciTools/tephi/issues/155#issuecomment-2454560289))
- [x] Implement changes so that tephi is in-line with these standards

### Repo Review Errors
- [x] PP301 - pytest isn't present in pyproject.toml. (#177)
- [x] GH212 - Need to add github groups (#179)
- [x] PC170 - Add a pygrep hook (#179)
- [x] PC901 - Add custom ci message (via dependabot) (#179)
- [x] PP309 - need to add filterwarnings(#213)

[ESadek-MO]

I think we should aim to include:

• PY005: - Has tests folder
• PP003: - Does not list wheel as a build-dep
• PP301: - Has pytest in project
• PP309: - Filter warnings specified
• PC110: - Uses black or ruff-format
• PC140: - Uses a type checker
• PC160: - Uses a spell checker
• PC170: - Uses PyGrep hooks (only needed if rST present)
• PC190: - Uses Ruff
• PC901: - Custom pre-commit CI message
• RF001: - Has Ruff config

With these being nice to haves:

• PP304: - Sets the log level in pytest
• PP305: - Specifies xfail_strict
• PP306: - Specifies strict config
• PP307: - Specifies strict markers
• GH212: - Require GHA update grouping
• PC180: - Uses a markdown formatter
• MY100: - Uses MyPy (pyproject config)

@bjlittle that sound about right?

[trexfeathers]

PC180: - Uses a markdown formatter

FYI we have been forced to ignore this one pretty much everywhere. I believe this is due to temporary limitations of the hardware most SciTools developers work on.