Update pre-commit to 2.18.1

[pyup-bot]

This PR updates pre-commit from 2.17.0 to 2.18.1.

Changelog

2.18.1

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

Fixes
- Fix regression for `repo: local` hooks running `python<3.7`
 - 2324 PR by asottile.

2.18.0

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

Features
- Keep `GIT_HTTP_PROXY_AUTHMETHOD` in git environ.
 - 2272 PR by VincentBerthier.
 - 2271 issue by VincentBerthier.
- Support both `cs` and `coursier` executables for coursier hooks.
 - 2293 PR by Holzhaus.
- Include more information in errors for `language_version` /
`additional_dependencies` for languages which do not support them.
 -  2315 PR by asottile.
- Have autoupdate preferentially pick tags which look like versions when
there are multiple equivalent tags.
 - 2312 PR by mblayman.
 - 2311 issue by mblayman.
- Upgrade `ruby-build`.
 - 2319 PR by jalessio.
- Add top level `default_install_hook_types` which will be installed when
`--hook-types` is not specified in `pre-commit install`.
 - 2322 PR by asottile.

Fixes
- Fix typo in help message for `--from-ref` and `--to-ref`.
 - 2266 PR by leetrout.
- Prioritize binary builds for R dependencies.
 - 2277 PR by lorenzwalthert.
- Fix handling of git worktrees.
 - 2252 PR by daschuer.
- Fix handling of `$R_HOME` for R hooks.
 - 2301 PR by jeff-m-sullivan.
 - 2300 issue by jeff-m-sullivan.
- Fix a rare race condition in change stashing.
 - 2323 PR by asottile.
 - 2287 issue by ian-h-chamberlain.

Updating
- Remove python3.6 support.  Note that pre-commit still supports running hooks
written in older versions, but pre-commit itself requires python 3.7+.
 - 2215 PR by asottile.
- pre-commit has migrated from the `master` branch to `main`.
 - 2302 PR by asottile.

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 #98