[gha] change stage description

.github/workflows/build.yml

@@ -13,7 +13,7 @@ jobs:
     - uses: actions/checkout@v2
       with:
         submodules: 'recursive'
-    - name: Build and push trunk container
+    - name: add PPA repository with latest boost
       if: matrix.os == 'ubuntu-20.04'
       run: sudo add-apt-repository ppa:mhier/libboost-latest 
     - name: install packages