Bump cachetools from 4.1.1 to 4.2.0 (#419)

Bumps [cachetools](https://github.com/tkem/cachetools) from 4.1.1 to 4.2.0.
- [Release notes](https://github.com/tkem/cachetools/releases)
- [Changelog](https://github.com/tkem/cachetools/blob/master/CHANGELOG.rst)
- [Commits](tkem/cachetools@v4.1.1...v4.2.0)

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

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

Author: dependabot-preview[bot]

requirements.txt

@@ -1,7 +1,7 @@
 cherry_picker==1.3.2
 aiohttp==3.7.3
 gidgethub==4.2.0
-cachetools==4.1.1
+cachetools==4.2.0
 redis==3.5.3
 celery==5.0.4
 sentry-sdk==0.17.3