Bump dgl from 2.1.0 to 2.2.1

Bumps [dgl](https://github.com/dmlc/dgl) from 2.1.0 to 2.2.1.
- [Release notes](https://github.com/dmlc/dgl/releases)
- [Changelog](https://github.com/dmlc/dgl/blob/master/NEWS.md)
- [Commits](dmlc/dgl@v2.1.0...v2.2.1)

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

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

requirements.txt

@@ -1,4 +1,4 @@
-dgl==2.1.0
+dgl==2.2.1
 torch==2.2.1
 lightning==2.4.0
 pymatgen==2024.8.9