Bump external/fmt from 6f26045 to 9f5f39c (#151)

Bumps [external/fmt](https://github.com/fmtlib/fmt) from `6f26045` to `9f5f39c`.
- [Release notes](https://github.com/fmtlib/fmt/releases)
- [Commits](fmtlib/fmt@6f26045...9f5f39c)

---
updated-dependencies:
- dependency-name: external/fmt
  dependency-type: direct:production
...

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