Use gcc-9 in CI

azure-pipelines.yml

@@ -27,7 +27,7 @@ jobs:
           sudo apt install -y python3-minimal g++-8 ccache
           python3 -m pip install pytest pytest-xdist
         displayName: Prepare System
-      - script: python3 -u tools/ci.py -B download --cxx g++-8 -T tools/gcc-8.dds
+      - script: python3 -u tools/ci.py -B download --cxx g++-8 -T tools/gcc-9.dds
         displayName: Full CI
       - publish: _build/dds
         artifact: DDS Executable - Linux
@@ -41,7 +41,7 @@ jobs:
       - script: |
           set -eu
           python3 -m pip install pytest pytest-xdist
-          python3 -u tools/ci.py -B download --cxx g++-8 -T tools/gcc-8.dds
+          python3 -u tools/ci.py -B download --cxx g++-8 -T tools/gcc-9.dds
         displayName: Build and Run Unit Tests
       - publish: _build/dds
         artifact: DDS Executable - macOS

tests/dds.py

@@ -124,7 +124,7 @@ class DDS:
     @property
     def default_builtin_toolchain(self) -> str:
         if os.name == 'posix':
-            return ':gcc-8'
+            return ':gcc-9'
         elif os.name == 'nt':
             return ':msvc'
         else: