👽 Normalize Towncrier config object as a dict

This is a compatibility change needed for Towncrier >= 22.12.0rc1
after it changed the internal object to be a `dataclass`.

Refs:
* twisted/towncrier#429
* twisted/towncrier#461

Resolves #76.

Co-Authored-By: davfsa <davfsa@gmail.com>
Co-Authored-By: Sviatoslav Sydorenko <webknjaz@redhat.com>

src/sphinxcontrib/towncrier/_towncrier.py

@@ -1,9 +1,16 @@
 """Towncrier related shims."""
 
+from contextlib import suppress as _suppress_exception
 from pathlib import Path
 from typing import Any, Dict
 
 
+with _suppress_exception(ImportError):
+    # NOTE: This will not raise an exception under Python >= 3.7, and is only
+    # NOTE: needed for Towncrier >= 22.12.0rc1 which doesn't support Python 3.6
+    from dataclasses import asdict as _dataclass_to_dict  # noqa: WPS433
+
+
 try:
     # Towncrier >= 22.8.0rc1
     # pylint: disable=import-error,no-name-in-module
@@ -24,7 +31,15 @@ def get_towncrier_config(
     """Return the towncrier config dictionary."""
     try:
         # Towncrier >= 19.9.0
-        return load_config_from_file(str(project_path), str(final_config_path))
+        config = load_config_from_file(
+            str(project_path), str(final_config_path),
+        )
     except TypeError:
         # Towncrier < 19.9.0
         return load_config_from_file(str(final_config_path))
+
+    if isinstance(config, dict):
+        # Towncrier < 22.12.0rc1
+        return config
+
+    return _dataclass_to_dict(config)