fix: move pytest to nativeBuildInputs so it's available in checkPhase

flake.nix

@@ -21,18 +21,16 @@
             python
             setuptools
             wheel
+            pytest
+            pytest-asyncio
           ];
           propagatedBuildInputs = with pythonPackages; [
             pyyaml
             pydantic
           ];
           doCheck = true;
-          checkInputs = with pythonPackages; [
-            pytest
-            pytest-asyncio
-          ];
           checkPhase = ''
-            pytest tests/ -x --tb=short -q
+            python -m pytest tests/ -x --tb=short -q
           '';
           pyproject = true;
           pyprojectFiles = [ "pyproject.toml" ];