Fix release-drafter v7 branch filtering (#323)

- filter-by-commitish is a config option, not a workflow input
- filter-by-range takes a semver range string, not a boolean
- Use filter-by-range: "3.x.x" to scope to 3.x releases
- Add filter-by-commitish: true in config to filter by target branch

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: gnodet

.github/release-drafter.yml

@@ -1,6 +1,7 @@
 name-template: $NEXT_PATCH_VERSION
 tag-template: plexus-utils-$NEXT_PATCH_VERSION
 version-template: $MAJOR.$MINOR.$PATCH
+filter-by-commitish: true
 
 categories:
   - title: ":boom: Breaking changes"

.github/workflows/release-drafter.yml

@@ -10,6 +10,6 @@ jobs:
       - uses: release-drafter/release-drafter@v7
         with:
           commitish: plexus-utils-3.x
-          filter-by-range: true
+          filter-by-range: "3.x.x"
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}