fix: specify Zig version to 0.15.0 in release workflow

.github/workflows/release.yaml

@@ -51,7 +51,7 @@ jobs:
       - name: Install Zig
         uses: korandoru/setup-zig@v1
         with:
-          zig-version: master
+          zig-version: 0.15.0
 
       - name: Build for ${{ matrix.triple }}
         run: |