Updated Testing section from Contributing.md

Author: p-r-a-v-i-n

docs/community/contributing.md

@@ -75,8 +75,7 @@ To run the tests, clone the repository, and then:
     # Setup the virtual environment
     python3 -m venv env
     source env/bin/activate
-    pip install -e .
-    pip install -r requirements.txt
+    pip install -e .[testing,optional,packaging]
 
     # Run the tests
     ./runtests.py