Try to test gcc 8 in CI

.github/workflows/tests.yml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        compiler: [g++-10, clang++-14]
+        compiler: [g++-8, g++-10, clang++-14]
         target: [Debug]
     steps:
     - uses: actions/checkout@v2
@@ -34,6 +34,32 @@ jobs:
       working-directory: build
       run: |
            CTEST_OUTPUT_ON_FAILURE=1 make test
+  test-linux-gcc-8:
+    runs-on: ubuntu-20.04
+    strategy:
+      fail-fast: false
+      matrix:
+        compiler: [g++-8]
+        target: [Debug]
+    steps:
+    - uses: actions/checkout@v2
+    - name: dependencies
+      run: |
+           sudo apt install gcc-8 g++-8 libgcc-8-dev
+           python3 -m pip install git+https://github.com/jeffkaufman/icdiff.git
+    - name: build
+      run: |
+           mkdir -p build
+           cd build
+           cmake .. \
+            -DCMAKE_BUILD_TYPE=${{matrix.target}} \
+            -DCMAKE_CXX_COMPILER=${{matrix.compiler}} \
+            -DLIBASSERT_BUILD_TESTING=On
+           make -j
+    - name: test
+      working-directory: build
+      run: |
+           CTEST_OUTPUT_ON_FAILURE=1 make test
   test-macos:
     runs-on: macos-14
     strategy: