Don't persist ccache stats across runs

.github/workflows/main.yml

@@ -110,6 +110,9 @@ jobs:
           echo WASI_SDK_CI_TOOLCHAIN_CMAKE_ARGS="$cmake_args" >> $GITHUB_ENV
         shell: bash
 
+      - name: Clear ccache statistics
+        run: ccache --zero-stats
+
       # Add some extra installed software on each runner as necessary.
       - name: Setup `wasmtime` for tests
         uses: bytecodealliance/actions/wasmtime/setup@v1