using local workdir. down running os.

.github/workflows/build-gcc.yml

@@ -17,7 +17,7 @@ jobs:
       ! contains(toJSON(github.event.commits.*.message), '[skip ci]') &&
       ! contains(toJSON(github.event.commits.*.message), '[skip github]')
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
 
     strategy:
       fail-fast: false
@@ -30,10 +30,7 @@ jobs:
 
     container:
       image: gcc:${{matrix.gcc_version}}
-      options: >-
-        -v /usr/local:/host_usr_local
-        -v "${{ github.workspace }}":/workspace
-        --workdir /workspace
+      options: -v /usr/local:/host_usr_local
 
     steps:
       - uses: actions/checkout@v1
@@ -55,16 +52,16 @@ jobs:
 
       - name: Configure
         run: >-
-          cmake -B /workspace/build
+          cmake -B build
           -DCMAKE_BUILD_TYPE=${{ matrix.build_type }}
-          -S /workspace
+          -S .
 
       - name: Build
         run: >-
-          cmake --build /workspace/build
+          cmake --build build
           --config ${{ matrix.build_type }}
           -- -j ${{steps.cores.outputs.count}}
 
       - name: Test
-        working-directory: /workspace/build
+        working-directory: build
         run: ctest --output-on-failure --build-config ${{ matrix.build_type }}