Drop SLES 12 support for EOL

builder/docker-compose.yml

@@ -89,17 +89,6 @@ services:
     image: r-builds:centos-8
     volumes:
       - ./integration/tmp:/tmp/output
-  opensuse-42:
-    command: ./build.sh
-    environment:
-      - R_VERSION=${R_VERSION}
-      - LOCAL_STORE=/tmp/output
-    build:
-      context: .
-      dockerfile: Dockerfile.opensuse-42
-    image: r-builds:opensuse-42
-    volumes:
-      - ./integration/tmp:/tmp/output
   opensuse-153:
     command: ./build.sh
     environment: