Temporarily disable CentOS 8 image builds because it's EOL

builder/docker-compose.yml

@@ -78,17 +78,17 @@ services:
     image: r-builds:centos-7
     volumes:
       - ./integration/tmp:/tmp/output
-  centos-8:
-    command: ./build.sh
-    environment:
-      - R_VERSION=${R_VERSION}
-      - LOCAL_STORE=/tmp/output
-    build:
-      context: .
-      dockerfile: Dockerfile.centos-8
-    image: r-builds:centos-8
-    volumes:
-      - ./integration/tmp:/tmp/output
+  # centos-8:
+  #   command: ./build.sh
+  #   environment:
+  #     - R_VERSION=${R_VERSION}
+  #     - LOCAL_STORE=/tmp/output
+  #   build:
+  #     context: .
+  #     dockerfile: Dockerfile.centos-8
+  #   image: r-builds:centos-8
+  #   volumes:
+  #     - ./integration/tmp:/tmp/output
   opensuse-42:
     command: ./build.sh
     environment: