actions: ci: Enable ccache

Reduces build time with full cache from 20 to ~3 minutes.

.github/workflows/ci.yml

@@ -22,16 +22,23 @@ jobs:
     - uses: actions/checkout@v2
 
     - 
-      name: Update ubuntu
+      name: Install dependencies
       run: |
         sudo apt update
         sudo apt-get install git cmake gcc g++ libboost1.67-all-dev python3-all-dev swig libpcre3-dev libxml2-dev
         sudo apt-get install liboce-foundation-dev liboce-modeling-dev liboce-ocaf-dev liboce-visualization-dev liboce-ocaf-lite-dev
+
+    -
+      name: ccache
+      uses: hendrikmuhs/ccache-action@v1
+
     - 
       name: Build ifcopenshell
       run: |
         mkdir build && cd build
         cmake \
+         -DCMAKE_C_COMPILER_LAUNCHER=ccache \
+         -DCMAKE_CXX_COMPILER_LAUNCHER=ccache \
          -DCMAKE_INSTALL_PREFIX=$PWD/install/ \
          -DCMAKE_BUILD_TYPE=Release \
          -DCMAKE_PREFIX_PATH=/usr \