Use SKIP_BUILD (#1681)

Author: aurexav

.github/workflows/release.yml

@@ -94,7 +94,7 @@ jobs:
           sudo mv ./wuh /usr/bin/wuh
       - name: Build ${{ matrix.runtime }} runtime
         id: srtool_build
-        if: ${{ env.FILTER == 'true' }}
+        if: ${{ env.SKIP_BUILD != 'true' }}
         uses: chevdor/srtool-actions@v0.9.2
         env:
           BUILD_OPTS: --features=on-chain-release-build