Bump pymongo from 3.10.1 to 4.6.3 in /build

Bumps [pymongo](https://github.com/mongodb/mongo-python-driver) from 3.10.1 to 4.6.3.
- [Release notes](https://github.com/mongodb/mongo-python-driver/releases)
- [Changelog](https://github.com/mongodb/mongo-python-driver/blob/master/doc/changelog.rst)
- [Commits](https://github.com/mongodb/mongo-python-driver/compare/3.10.1...4.6.3)

---
updated-dependencies:
- dependency-name: pymongo
  dependency-type: direct:production
...

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

build/requirements.txt

@@ -1,5 +1,5 @@
 geojson==2.5.0
 jsonschema==3.2.0
 networkx==2.4
-pymongo==3.10.1
+pymongo==4.6.3
 pyzmq==19.0.0