CI: bump to v4

Signed-off-by: Tianling Shen <[email protected]>

.github/workflows/multi-arch-test-build.yml

@@ -78,7 +78,7 @@ jobs:
           echo "PACKAGES=$PACKAGES" >> $GITHUB_ENV
 
       - name: Build
-        uses: immortalwrt/gh-action-sdk@v3
+        uses: immortalwrt/gh-action-sdk@v4
         env:
           ARCH: ${{ matrix.arch }}-${{ env.BRANCH }}
           FEEDNAME: packages_ci