add pyyp3 and comment.

Author: oakbani

.travis.yml

@@ -63,6 +63,10 @@ jobs:
         FULLSTACK_TEST_REPO=ProdTesting
     - stage: 'Test'
       python: "pypy"
+      before_install:
+        - pip install "cryptography>=1.3.4,<=3.1.1" # installing in before_install doesn't re-install a latest version of the same package in the next stage.
+    - stage: 'Test'
+      python: "pypy3"
       before_install:
         - pip install "cryptography>=1.3.4,<=3.1.1"
     - stage: 'Test'