Rename ``pythonpath`` plugin to ``python_path``

Fix #9636.

changelog/9636.bugfix.rst

@@ -0,0 +1 @@
+The ``pythonpath`` plugin was renamed to ``python_path``. This avoids a conflict with the ``pytest-pythonpath`` plugin.

src/_pytest/config/__init__.py

@@ -254,7 +254,7 @@ default_plugins = essential_plugins + (
     "warnings",
     "logging",
     "reports",
-    "pythonpath",
+    "python_path",
     *(["unraisableexception", "threadexception"] if sys.version_info >= (3, 8) else []),
     "faulthandler",
 )

testing/test_config.py

@@ -1275,7 +1275,7 @@ def test_load_initial_conftest_last_ordering(_config_for_test):
         ("_pytest.config", "nonwrapper"),
         (m.__module__, "nonwrapper"),
         ("_pytest.legacypath", "nonwrapper"),
-        ("_pytest.pythonpath", "nonwrapper"),
+        ("_pytest.python_path", "nonwrapper"),
         ("_pytest.capture", "wrapper"),
         ("_pytest.warnings", "wrapper"),
     ]

testing/test_python_path.py

@@ -81,7 +81,7 @@ def test_no_ini(pytester: Pytester, file_structure) -> None:
 
 
 def test_clean_up(pytester: Pytester) -> None:
-    """Test that the pythonpath plugin cleans up after itself."""
+    """Test that the plugin cleans up after itself."""
     # This is tough to test behaviorly because the cleanup really runs last.
     # So the test make several implementation assumptions:
     # - Cleanup is done in pytest_unconfigure().