Fix CI. Explicitly install all three compilers. (#19)

* Fix CI by explicitly installing compilers.  Also add GCC 14 to CI.

Author: BenBrock

.github/workflows/ci.yml

@@ -24,7 +24,7 @@ jobs:
     runs-on: 'ubuntu-latest'
     strategy:
       matrix:
-        cxx: [g++-13, g++-12, g++-11]
+        cxx: [g++-14, g++-13, g++-12, g++-11]
     name: ${{ matrix.cxx }}
     env:
       CXX: ${{ matrix.cxx }}
@@ -34,7 +34,7 @@ jobs:
       run: |
         sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y
         sudo apt-get update -y
-        sudo apt-get install g++-13
+        sudo apt-get install g++-11 g++-12 g++-13 g++-14
         cmake -B build
     - name: Build
       run: make -C build -j `nproc`