Bump shellingham from 1.5.3 to 1.5.4

Bumps [shellingham](https://github.com/sarugaku/shellingham) from 1.5.3 to 1.5.4.
- [Release notes](https://github.com/sarugaku/shellingham/releases)
- [Changelog](https://github.com/sarugaku/shellingham/blob/master/CHANGELOG.rst)
- [Commits](sarugaku/shellingham@1.5.3...1.5.4)

---
updated-dependencies:
- dependency-name: shellingham
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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