Bump pre-commit from 0.15.0 to 2.6.0 (#507)

Bumps [pre-commit](https://github.com/pre-commit/pre-commit) from 0.15.0 to 2.6.0.
- [Release notes](https://github.com/pre-commit/pre-commit/releases)
- [Changelog](https://github.com/pre-commit/pre-commit/blob/master/CHANGELOG.md)
- [Commits](pre-commit/pre-commit@v0.15.0...v2.6.0)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

tests/dev_requirements.txt

@@ -1,5 +1,5 @@
 bumpversion==0.5.3
-pre-commit==0.15.0
+pre-commit==2.6.0
 pytest>=3.6
 pytest-cov
 flake8