ENH Do not always install libffi-devel

Author: thomasjpfan

.github/workflows/wheels.yml

@@ -51,6 +51,7 @@ jobs:
         - os: ubuntu-latest
           python: "310"
           platform: manylinux_x86_64
+          install_libffi_devel: "1"
 
         # macos builds
         - os: macos-latest
@@ -86,8 +87,10 @@ jobs:
           CIBW_BUILD_VERBOSITY: 3
           CIBW_BEFORE_BUILD: bash {project}/tools/wheels/cibw_before_build.sh {project}
           CIBW_BEFORE_TEST: pip install -r {project}/test_requirements.txt
-          # Installs libffi so that cffi can be built from source if needed
-          CIBW_BEFORE_TEST_LINUX: yum install -y libffi-devel && pip install -r {project}/test_requirements.txt
+          # Installs libffi so that cffi can be built from source when needed
+          CIBW_BEFORE_TEST_LINUX: >
+            [[ "${{ matrix.install_libffi_devel }}" == "1" ]] && yum install -y libffi-devel;
+            pip install -r {project}/test_requirements.txt
           CIBW_TEST_COMMAND:  bash {project}/tools/wheels/cibw_test_command.sh {project}
 
       - uses: actions/upload-artifact@v2