Fixed SQLite3 1.4.0 build issues.
Fixed SQLite3 1.4.0 build issues.

Rails 5.2.x doesn't support SQLite3 yet it seems. By not restricting
SQLite3 to 1.3.x, we'll end up with the following errors:

    LoadError: Error loading the 'sqlite3' Active Record adapter.
      Missing a gem it depends on? can't activate sqlite3 (~> 1.3.6),
      already activated sqlite3-1.4.0. Make sure all dependencies are
      added to Gemfile.

bkuhlmann/tokener,bkuhlmann/tokener,bkuhlmann/tokener