update ccache

fix ccache implementation

.github/workflows/build.yml

@@ -12,14 +12,19 @@ jobs:
     steps:
       - name: Checkout code
         uses: actions/checkout@v2
-
+      - name: Prepare ccache timestamp
+        id: ccache_cache_timestamp
+        shell: cmake -P {0}
+        run: |
+          string(TIMESTAMP current_date "%Y-%m-%d-%H;%M;%S" UTC)
+          message("::set-output name=timestamp::${current_date}")
       - name: cache
         uses: actions/cache@v2
         with:
-          path: $HOME/.ccache
-          key: build-ccache
+          path: ~/.ccache
+          key: build-ccache-${{ steps.ccache_cache_timestamp.outputs.timestamp }}
           restore-keys: |
-            build-ccache
+            build-ccache-
       - name: Build binary
         run: |
               mkdir -p "$HOME/.ccache"