Bump deepmd-kit[cpu] from 3.0.2 to 3.1.2

Bumps [deepmd-kit[cpu]](https://github.com/deepmodeling/deepmd-kit) from 3.0.2 to 3.1.2.
- [Release notes](https://github.com/deepmodeling/deepmd-kit/releases)
- [Commits](deepmodeling/deepmd-kit@v3.0.2...v3.1.2)

---
updated-dependencies:
- dependency-name: deepmd-kit[cpu]
  dependency-version: 3.1.2
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

requirements.txt

@@ -1,4 +1,4 @@
-deepmd-kit[cpu]==3.0.2
+deepmd-kit[cpu]==3.1.2
 dpgen==0.13.2
 dpdispatcher==0.6.10
 dargs