try to disable warnings

Author: Carreau

.github/workflows/wheel.yaml

@@ -14,7 +14,7 @@ jobs:
       CIBW_TEST_COMMAND: pytest --pyargs numcodecs
       CIBW_TEST_REQUIRES: pytest
       CIBW_SKIP: "*27* pp* *35*"
-      CIBW_ENVIRONMENT: "DISABLE_NUMCODECS_AVX2=1"
+      CIBW_ENVIRONMENT: 'DISABLE_NUMCODECS_AVX2=1 CFLAGS="$CFLAGS -w"'
       CIBW_ENVIRONMENT_MACOS: "MACOSX_DEPLOYMENT_TARGET=10.9 DISABLE_NUMCODECS_AVX2=1"
 
     steps: