chore(install/bundle): set Dockerfile build from new branch name
chore(install/bundle): set Dockerfile build from new branch name

We've just change php7 branch as the master branch, and php5 version turned into legacy.
To make docker automated build work correctly, the branch name specify now changed.

UniversalOJ/UOJ-System,UniversalOJ/UOJ-System,UniversalOJ/UOJ-System,UniversalOJ/UOJ-System,UniversalOJ/UOJ-System,UniversalOJ/UOJ-System,UniversalOJ/UOJ-System