⬆️ Update flit-core requirement from <3,>=2 to >=2,<4

Updates the requirements on [flit-core](https://github.com/pypa/flit) to permit the latest version.
- [Changelog](https://github.com/pypa/flit/blob/main/doc/history.rst)
- [Commits](pypa/flit@2.0...3.10.1)

---
updated-dependencies:
- dependency-name: flit-core
  dependency-type: direct:production
...

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

pyproject.toml

@@ -1,5 +1,5 @@
 [build-system]
-requires = ["flit_core >=2,<3"]
+requires = ["flit_core >=2,<4"]
 build-backend = "flit_core.buildapi"
 
 [tool.flit.metadata]