ci: add support of ccache

.github/workflows/macos-linux-conda.yml

@@ -15,6 +15,12 @@ jobs:
     steps:
     - uses: actions/checkout@v2
 
+    - name: ccache
+      uses: hendrikmuhs/ccache-action@v1
+      with:
+        key: ${{ matrix.os }}-${{ matrix.type }}
+        max-size: 1G
+
     - name: Checkout submodules
       run: |
         git submodule update --init
@@ -32,13 +38,15 @@ jobs:
         conda activate pinocchio
         conda install cmake -c main
         conda install llvm-openmp libcxx=11 -c conda-forge
-    
+
     - name: Build Pinocchio
       shell: bash -l {0}
       run: |
         conda activate pinocchio
         echo $CONDA_PREFIX
-        
+
+        export PATH="/usr/lib/ccache:/usr/local/opt/ccache/libexec:$PATH"
+
         mkdir build
         cd build