Merge branch 'fix_gemfile' into 'master'

Fix gemfile

1. replace `"` to `'` in Gemfile.

2. change `require: nil` to `require: false`.
`require: nil` and `require: false` get same result, but i think we shouldn't write it differently in other places.

3. set version for gems.
better gem's version control for prevent dependency errors.

See merge request !5078