Bump pymongo from 4.6.3 to 4.15.0

Bumps [pymongo](https://github.com/mongodb/mongo-python-driver) from 4.6.3 to 4.15.0.
- [Release notes](https://github.com/mongodb/mongo-python-driver/releases)
- [Changelog](https://github.com/mongodb/mongo-python-driver/blob/master/doc/changelog.rst)
- [Commits](mongodb/mongo-python-driver@4.6.3...4.15.0)

---
updated-dependencies:
- dependency-name: pymongo
  dependency-version: 4.15.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

requirements.txt

@@ -9,7 +9,7 @@ firebase-admin
 slack-sdk
 google-cloud-core
 google-cloud-storage
-pymongo==4.6.3
+pymongo==4.15.0
 tinydb==4.8.0
 pytesseract
 Pillow