Use environment variables instead of contexts

I swear I read the docs.

Author: mdpiper

.github/workflows/test.yml

@@ -68,7 +68,7 @@ jobs:
 
     env:
       LIBRARY_PREFIX: $env:CONDA_PREFIX\Library
-      FC: $env:CONDA_PREFIX\Library\bin\flang-new.exe
+      FC: ${env:LIBRARY_PREFIX}\bin\flang-new.exe
 
     steps:
       - uses: actions/checkout@v4
@@ -91,7 +91,7 @@ jobs:
       - name: Configure, build, and install
         working-directory: ${{ github.workspace }}/build
         run: |
-          cmake .. -G Ninja -DCMAKE_Fortran_COMPILER="${{ env.FC }}" -DCMAKE_INSTALL_PREFIX="${{ env.LIBRARY_PREFIX }}" -DCMAKE_BUILD_TYPE=Release
+          cmake .. -G Ninja -DCMAKE_Fortran_COMPILER=${env:FC} -DCMAKE_INSTALL_PREFIX=${env:LIBRARY_PREFIX} -DCMAKE_BUILD_TYPE=Release
           cmake --build . --target install --config Release
 
       - name: Check (for humans)