Bump pkg-config from 0.3.30 to 0.3.31 (#1090)

Bumps [pkg-config](https://github.com/rust-lang/pkg-config-rs) from 0.3.30 to 0.3.31.
- [Changelog](https://github.com/rust-lang/pkg-config-rs/blob/master/CHANGELOG.md)
- [Commits](rust-lang/pkg-config-rs@0.3.30...0.3.31)

---
updated-dependencies:
- dependency-name: pkg-config
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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