Remove github3.py from our zuul config

It seems that zuul gets a 403 when trying to set up this app
installation which implies the repo on the github side disabled us. This
403 stops zuul's startup process so we remove it.

Change-Id: I97e4f174cd083a6b0bbe1fafaf6664720923ac9e

zuul.d/projects.yaml

@@ -6253,11 +6253,6 @@
             required-projects:
               - opendev/system-config
 
-- project:
-    name: sigmavirus24/github3.py
-    third-party-check:
-      jobs:
-        - tox-py35-on-zuul
 - project:
     name: ttygroup/boartty
     templates:

zuul/main.yaml

@@ -1468,7 +1468,6 @@
               - novnc/novnc
               - openvswitch/ovs
               - pytest-dev/pytest-testinfra
-              - sigmavirus24/github3.py
               - sqlalchemy/dogpile.cache
               - stackhpc/ansible-role-libvirt-host
               - stackhpc/ansible-role-libvirt-vm
@@ -1646,7 +1645,6 @@
               - cherrypy/cherrypy
               - pytest-dev/pytest-testinfra
               - pravega/zookeeper-operator
-              - sigmavirus24/github3.py
               - sphinx-contrib/openapi
               - sqlalchemy/dogpile.cache
       googlesource: