Update pre-commit to 1.21.0

[pyup-bot]

This PR updates pre-commit from 1.20.0 to 1.21.0.

Changelog

1.21.0

===================

Features
- Add `conda` as a new `language`.
 - 1204 issue by xhochy.
 - 1232 PR by xhochy.
- Add top-level configuration `files` for file selection.
 - 1220 issue by TheButlah.
 - 1248 PR by asottile.
- Rework `--verbose` / `verbose` to be more consistent with normal runs.
 - 1249 PR by asottile.
- Add support for the `pre-merge-commit` git hook.
 - 1210 PR by asottile.
 - this requires git 2.24+.
- Add `pre-commit autoupdate --freeze` which produces "frozen" revisions.
 - 1068 issue by SkypLabs.
 - 1256 PR by asottile.
- Display hook runtime duration when run with `--verbose`.
 - 1144 issue by potiuk.
 - 1257 PR by asottile.

Fixes
- Produce better error message when erroneously running inside of `.git`.
 - 1219 issue by Nusserdt.
 - 1224 PR by asottile.
 - Note: `git` has since fixed this bug: git/git36fd304d
- Produce better error message when hook installation fails.
 - 1250 issue by asottile.
 - 1251 PR by asottile.
- Fix cloning when `GIT_SSL_CAINFO` is necessary.
 - 1253 issue by igankevich.
 - 1254 PR by igankevich.
- Fix `pre-commit try-repo` for bare, on-disk repositories.
 - 1258 issue by webknjaz.
 - 1259 PR by asottile.
- Add some whitespace to `pre-commit autoupdate` to improve terminal autolink.
 - 1261 issue by yhoiseth.
 - 1262 PR by yhoiseth.

Misc.
- Minor code documentation updates.
 - 1200 PR by ryanrhee.
 - 1201 PR by ryanrhee.

Links

• PyPI: https://pypi.org/project/pre-commit
• Changelog: https://pyup.io/changelogs/pre-commit/
• Repo: https://github.com/pre-commit/pre-commit

[pyup-bot]

Closing this in favor of #142