Fixed 5.6.28 URL

Author: MySQL Build Team

5.6/Dockerfile

@@ -1,6 +1,6 @@
 FROM oraclelinux:latest
 
-ENV PACKAGE_URL https://repo.mysql.com/yum/mysql-5.6-community/docker/x86_64/
+ENV PACKAGE_URL https://repo.mysql.com/yum/mysql-5.6-community/docker/x86_64/mysql-community-server-minimal-5.6.28-2.el7.x86_64.rpm
 
 # Install server
 RUN rpmkeys --import http://repo.mysql.com/RPM-GPG-KEY-mysql \