docs(contributing): switch to rattler-build on Contributing packages page

Author: lucascolley

blog/2020-02-04-gsoc.md

@@ -33,7 +33,6 @@ detailed listing of the issues that need work.
     We have a large backlog of maintenance and refactoring issues that
     are great for people with a range of experience from beginners to
     true code ninjas.
-
     - Integration Testing for the Autotick Bot
 
       > Run true integration testing on a copy of the graph to better