docs: Changed release date of v0.25.0 to UNRELEASED.

Author: seifertm

docs/reference/changelog.rst

@@ -2,7 +2,7 @@
 Changelog
 =========
 
-0.25.0 (2024-11-07)
+0.25.0 (UNRELEASED)
 ===================
 - Deprecated: Added warning when asyncio test requests async ``@pytest.fixture`` in strict mode. This will become an error in a future version of flake8-asyncio. `#979 <https://github.com/pytest-dev/pytest-asyncio/pull/979>`_