chore(deps): bump pymongo in /reference-apps/fastapi

Bumps [pymongo](https://github.com/mongodb/mongo-python-driver) from 4.15.5 to 4.16.0.
- [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@4.15.5...4.16.0)

---
updated-dependencies:
- dependency-name: pymongo
  dependency-version: 4.16.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

reference-apps/fastapi/requirements.txt

@@ -12,7 +12,7 @@ asyncpg==0.31.0
 aiomysql==0.3.2
 cryptography>=41.0.0  # Required for MySQL caching_sha2_password auth
 motor==3.7.1
-pymongo==4.15.5
+pymongo==4.16.0
 
 # Redis and Caching
 # redis 4.3.0+ required for redis.asyncio.cluster module used by fastapi-cache2