split one test into three

(I am trying to debug the third one on the Mac, and this makes it easier.)

tests.py

@@ -152,6 +152,7 @@ def test_install_environment_wrong_toolchain(tmp_path):
             script_dir=(tmp_path),
         )
 
+
 def test_install_environment_wrong_mpsd_release(tmp_path):
     """Test exception is raised for non-existing mpsd release."""
     # Expect an Exception when wrong mpsd_release is provided (part of
@@ -163,6 +164,7 @@ def test_install_environment_wrong_mpsd_release(tmp_path):
             script_dir=(tmp_path),
         )
 
+
 def test_install_environment_zlib(tmp_path):
     """Test installation of toolchain."""
     # prepare a test of global generic with only zlib to test the installation