Also pack source for release.

The automatically created URLs from archives are not stable
  https://github.com/orgs/community/discussions/46034
so also craete a release artifact that we packed ourselves and
will stay as-is.

.github/workflows/verible-ci.yml

@@ -436,9 +436,34 @@ jobs:
         rm c:/users/runneradmin/_bazel_runneradmin/*/java.log
 
 
+  PackReleaseSource:
+    name: 📦 Pack Sources
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+
+    - name: Pack Sources
+      run: |
+        VERSION=$(git describe --match=v*)
+        OUT_SRC=verible-v${VERSION}
+
+        mkdir ../${OUT_SRC}
+        cp -r . ../${OUT_SRC}
+
+        tar --exclude=.git -cvzf ${OUT_SRC}.tar.gz ../${OUT_SRC}
+
+    - name: 📤 Upload Source tar
+      uses: actions/upload-artifact@v4
+      with:
+        path: verible-*.tar.gz
+
   Release:
     name: 📦 Release
-    needs: [ Check, MacOsBuild, WindowsBuild, PrepareVSPlugin ]
+    needs: [ Check, PackReleaseSource, MacOsBuild, WindowsBuild, PrepareVSPlugin ]
     runs-on: ubuntu-20.04
     permissions:
       contents: write