chore(ci): disable centos7 build

.github/workflows/build_slim_packages.yaml

@@ -18,7 +18,7 @@ jobs:
         - erl23.2.7.2-emqx-2
         os:
         - ubuntu20.04
-        - centos7
+        #- centos7
 
     container: emqx/build-env:${{ matrix.erl_otp }}-${{ matrix.os }}