Use predefined types for pre-commit over file endings

[hofbi]

pre-commit has some predefined types that match the correct extensions. The jsonnet type matches https://github.com/pre-commit/identify/blob/40af39f8124a4e8029ff3716c2b0bbf2e1e5fb1e/identify/extensions.py#L139 and https://github.com/pre-commit/identify/blob/40af39f8124a4e8029ff3716c2b0bbf2e1e5fb1e/identify/extensions.py#L151 which are exactly the file endings used before

[johnbartholomew]

Thanks for the contribution! I'm not very familiar with the pre-commit tool, but this looks ok.

[coveralls]

coverage: 44.109%. remained the same
when pulling 751aedf on hofbi:patch-1
into 604f4d7 on google:master.