Fix Docker image name

Author: TheAssassin

.github/workflows/main.yml

@@ -14,9 +14,9 @@ jobs:
       matrix:
         include:
           - ARCH: x86_64
-            DOCKER_IMAGE: quay.io/appimage/appimagebuild
+            DOCKER_IMAGE: quay.io/appimage/appimagebuild:centos7-x86_64
           - ARCH: i686
-            DOCKER_IMAGE: quay.io/appimage/appimagebuild-i386
+            DOCKER_IMAGE: quay.io/appimage/appimagebuild:centos7-i386
       fail-fast: false
 
     name: ${{ matrix.BUILD_TYPE }} ${{ matrix.ARCH }}