flit: disable tests for PEP 668 (#230706)

The install tests call `pip` directly, and that doesn't work with PEP
668 anymore.

See #229166

pkgs/development/python-modules/flit/default.nix

@@ -43,6 +43,11 @@ buildPythonPackage rec {
   disabledTests = [
     # needs some ini file.
     "test_invalid_classifier"
+    # calls pip directly. disabled for PEP 668
+    "test_install_data_dir"
+    "test_install_module_pep621"
+    "test_symlink_data_dir"
+    "test_symlink_module_pep621"
   ];
 
   meta = with lib; {