Bump pymatgen from 2024.11.13 to 2025.4.20 (#1184)

Bumps [pymatgen](https://github.com/materialsproject/pymatgen) from 2024.11.13 to 2025.4.20.
- [Release notes](https://github.com/materialsproject/pymatgen/releases)
- [Changelog](https://github.com/materialsproject/pymatgen/blob/master/docs/CHANGES.md)
- [Commits](materialsproject/pymatgen@v2024.11.13...v2025.4.20)

---
updated-dependencies:
- dependency-name: pymatgen
  dependency-version: 2025.4.20
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

pyproject.toml

@@ -123,7 +123,7 @@ strict-openff = [
     "monty==2025.3.3",
     "openmm-mdanalysis-reporter==0.1.0",
     "openmm==8.1.1",
-    "pymatgen==2024.11.13", # TODO: open ff is extremely sensitive to pymatgen version
+    "pymatgen==2025.4.20", # TODO: open ff is extremely sensitive to pymatgen version
     "mdanalysis==2.9.0"
 ]
 strict-forcefields = [