Simplify configure

Author: toroidal-code

.github/workflows/test.yml

@@ -36,7 +36,7 @@ jobs:
       if: ${{ matrix.compiler != 'native' }}
 
     - name: Configure
-      run: cmake -B build -DCPPSPEC_BUILD_TESTS=YES -DCMAKE_C_COMPILER="$CC" -DCMAKE_CXX_COMPILER="$CXX"
+      run: cmake -B build -DCPPSPEC_BUILD_TESTS=YES
 
     - name: Build
       run: cmake --build build --config Release