Update changelog for release

CHANGELOG.rst

@@ -1,8 +1,19 @@
 Changelog
 ---------
 
-*unreleased*
-~~~~~~~~~~~~
+23.0 - 2023-01-08
+~~~~~~~~~~~~~~~~~
+
+* Allow `"extra"` to be `None` in the marker environment (:issue:`650`)
+* Refactor `tags._generic_api` to use `EXT_SUFFIX` (:issue:`607`)
+* Correctly handle trailing whitespace on URL requirements
+* Fix typing for ``specifiers.BaseSpecifier.filter()`` (:issue:`643`)
+* Use stable Python 3.11 in tests (:issue:`641`)
+* Add a test case for non-normalised specifiers
+* Reorder specifier matching to try longer names first
+* Use regular expression from specifiers as-is for requirement parsing
+* Move to ``src/`` layout (:issue:`626`)
+* Remove ``__about__`` file, in favour of keeping constants in ``__init__`` (:issue:`626`)
 
 No unreleased changes.