Merge pull request rails#43480 from hachi8833/hachi8833-patch-1

Fix typo in upgrading_ruby_on_rails.md [ci-skip]

Author: guilleiguaran

guides/source/upgrading_ruby_on_rails.md

@@ -102,7 +102,7 @@ The private API of `ActiveSupport::Dependencies` has been deleted. That includes
 
 A few of highlights:
 
-* If you used `ActiveSupport::Dependencies.constantize` or ``ActiveSupport::Dependencies.safe_constantize`, just change them to `String#constantize` or `String#safe_constantize`.
+* If you used `ActiveSupport::Dependencies.constantize` or `ActiveSupport::Dependencies.safe_constantize`, just change them to `String#constantize` or `String#safe_constantize`.
 
   ```ruby
   ActiveSupport::Dependencies.constantize("User") # NO LONGER POSSIBLE