ci: update zig

Author: CWood-sdf

.github/workflows/ci.yaml

@@ -16,7 +16,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: mlugg/setup-zig@v1
         with:
-          version: 0.14.0
+          version: 0.15.0
       - name: zig build
         run: |
           cd zig