Bump flit from 3.8.0 to 3.9.0 (#10)

Bumps [flit](https://github.com/pypa/flit) from 3.8.0 to 3.9.0.
- [Changelog](https://github.com/pypa/flit/blob/main/doc/history.rst)
- [Commits](pypa/flit@3.8.0...3.9.0)

---
updated-dependencies:
- dependency-name: flit
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

pyproject.toml

@@ -27,7 +27,7 @@ dependencies = []
 dev = [
     "attribution==1.6.2",
     "black==23.3.0",
-    "flit==3.8.0",
+    "flit==3.9.0",
     "mypy==1.2.0",
     "ufmt==2.1.0",
     "usort==1.0.6",