Limited the permitted versions of mypy and related django-slugs, to avoid issues related to using Django-1.11. Update to latest versions when we've moved to Django 2.2.x

 - Legacy-Id: 17186

Author: levkowetz

requirements3.txt

@@ -20,7 +20,7 @@ django-markup>=1.1
 django-password-strength>=1.2.1
 django-referrer-policy>=1.0
 django-simple-history>=2.3.0
-django-stubs>=1.2.0
+django-stubs==1.3.0
 django-tastypie>=0.13.2
 django-webtest>=1.9.7
 django-widget-tweaks>=1.3
@@ -36,7 +36,7 @@ jwcrypto>=0.4.0			# for signed notifications
 #lxml>=3.4.0                    # from PyQuery; 
 markdown2>=2.3.8
 mock>=2.0.0
-mypy				# Version requirements determined by django-stubs.
+mypy==0.750			# Version requirements determined by django-stubs.
 mysqlclient>=1.3.13
 oauth2client>=4.0.0		# required by google-api-python-client, but not always pulled in
 patch>=1.16,<2.0