Bump pandas from 1.2.5 to 1.3.1

Bumps [pandas](https://github.com/pandas-dev/pandas) from 1.2.5 to 1.3.1.
- [Release notes](https://github.com/pandas-dev/pandas/releases)
- [Changelog](https://github.com/pandas-dev/pandas/blob/master/RELEASE.md)
- [Commits](pandas-dev/pandas@v1.2.5...v1.3.1)

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

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