Use explicit YAMLLINT settings

[henrygab]

In particular, the following notable changes are made:

1. comments cause only warnings
2. disable warning about missing document-start marker '---'
3. warn if YAML has document-end marker '...'
4. disable some float values (+inf, -inf, NaN)
5. Float values require digits before the decimal point
6. Disable line length maximum
7. Forbit implicit use of octal values (too error prone!)
8. temporarily disable truthy, because it warns on GitHub Actions use of on....

[SpenceKonde]

Thaaanks