Update changelog for 0.25.0 (#1389)

This is to prepare for the 0.25.0 release.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 977acba..502545a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,8 +17,7 @@
 * Particular sub-systems are identified using parentheses, e.g. `(bzlmod)` or
   `(docs)`.
 
-
-## Unreleased
+## [0.25.0] - 2023-08-22
 
 ### Changed
 
@@ -40,6 +39,8 @@
 * (gazelle) Stop generating unnecessary imports.
 * (toolchains) s390x supported for Python 3.9.17, 3.10.12, and 3.11.4.
 
+[0.25.0]: https://github.com/bazelbuild/rules_python/releases/tag/0.25.0
+
 ## [0.24.0] - 2023-07-11
 
 ### Changed