fix(ci): replace actions/checkout with manual git clone in release

actions/checkout uses GITHUB_SERVER_URL=http://localhost:3002 which is
unreachable from inside the Docker container. Use the public Forgejo URL
directly, matching the pattern used by package.yml.

.forgejo/workflows/release.yml

@@ -12,7 +12,10 @@ jobs:
   build:
     runs-on: [self-hosted, hestia]
     steps:
-      - uses: actions/checkout@v4
+      - name: checkout
+        run: |
+          git clone --branch "${GITHUB_REF_NAME}" --depth 1 \
+            "https://git.breadway.dev/${GITHUB_REPOSITORY}.git" .
 
       - name: build
         run: cargo build --release --locked