Bump postcss-normalize-timing-functions from 5.0.1 to 5.1.0

Bumps [postcss-normalize-timing-functions](https://github.com/cssnano/cssnano) from 5.0.1 to 5.1.0.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/postcss-normalize-timing-functions@[email protected])

---
updated-dependencies:
- dependency-name: postcss-normalize-timing-functions
  dependency-type: indirect
  update-type: version-update:semver-minor
...

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