Update release process docs to use new changelog tool

Replace reference to tools/git/changelog.pl with the new
tools/changelog/changelog.py invocation using uv run.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: cmcfarlen

doc/developer-guide/release-process/index.en.rst

@@ -67,8 +67,8 @@ Build
 
 #. Generate or update the CHANGELOG for the next release.  ::
 
-      ./tools/git/changelog.pl -o apache -r trafficserver -m X.Y.Z >
-      CHANGELOG-X.Y.Z
+      uv run --project tools/changelog python tools/changelog/changelog.py \
+        -o apache -r trafficserver -m X.Y.Z --use-gh > CHANGELOG-X.Y.Z
 
 #. Commit this file to the repository and push it to the release branch.