Bump libm from 0.2.8 to 0.2.11

Bumps [libm](https://github.com/rust-lang/libm) from 0.2.8 to 0.2.11.
- [Release notes](https://github.com/rust-lang/libm/releases)
- [Changelog](https://github.com/rust-lang/libm/blob/master/CHANGELOG.md)
- [Commits](rust-lang/libm@0.2.8...libm-v0.2.11)

---
updated-dependencies:
- dependency-name: libm
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]