fix: restore shasum fallback for macOS in release workflow

Author: PySudo

.github/workflows/release.yml

@@ -153,9 +153,13 @@ jobs:
             tar czf "${PKG}.tar.gz" "$PKG"
           fi
 
-          # Generate SHA256 checksum (sha256sum is available on all runners)
+          # Generate SHA256 checksum
           ASSET=$(ls "${PKG}.tar.gz" "${PKG}.zip" 2>/dev/null | head -1)
-          sha256sum "$ASSET" > "${ASSET}.sha256"
+          if command -v sha256sum >/dev/null 2>&1; then
+            sha256sum "$ASSET" > "${ASSET}.sha256"
+          else
+            shasum -a 256 "$ASSET" > "${ASSET}.sha256"
+          fi
           echo "=== Packaged ==="
           ls -la