Build for both Ubuntu LTS currently alive (18.04 will be out of support in a couple of days)

Signed-off-by: Alexis Maiquez <almamu@almamu.com>

.github/workflows/cmake.yml

@@ -12,10 +12,13 @@ env:
 
 jobs:
   build:
+    strategy:
+      matrix:
+        os: [ubuntu-22.04, ubuntu-20.04]
     # The CMake configure and build commands are platform agnostic and should work equally well on Windows or Mac.
     # You can convert this to a matrix build if you need cross-platform coverage.
     # See: https://docs.github.com/en/free-pro-team@latest/actions/learn-github-actions/managing-complex-workflows#using-a-build-matrix
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
 
     steps:
     - uses: actions/checkout@v3