chore(deps): bump thirdparty/eigen from 2d4c9b4 to 7ad7c1d

Bumps [thirdparty/eigen](https://gitlab.com/libeigen/eigen) from `2d4c9b4` to `7ad7c1d`.
- [Release notes](https://gitlab.com/libeigen/eigen/tags)
- [Commits](https://gitlab.com/libeigen/eigen/compare/2d4c9b400cca33d2f5cf316efc7151236244edb1...7ad7c1d5c59ab0bf87f83003283f0cc8357789bd)

---
updated-dependencies:
- dependency-name: thirdparty/eigen
  dependency-type: direct:production
...

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