hotfix: pin flask and flask extensions (#37)

setup.py

@@ -18,15 +18,16 @@
         # TODO: remove this pin on click once this celery issue is resolved:
         # https://github.com/celery/celery/issues/6768
         'click>=7.0,<8.0',
+        # TODO: remove these pins on flask/extensions once the celery issue above is resolved
         'flask-restx>=0.4.0',
+        'Flask-SQLAlchemy>=2.5.1,<3.0.0',
+        'Flask-WTF>=0.14.3,<1.0.0',
+        'Flask-DebugToolbar>=0.11.0,<1.0.0',
+        'Flask-Login>=0.5.0,<1.0.0',
         'gunicorn>=19.1.1',
         'gevent>=1.1.1',
         'eventlet>=0.17.4',
         'requests>=2.7.0',
-        'Flask-SQLAlchemy>=1.0',
-        'Flask-WTF>=0.10.0',
-        'Flask-DebugToolbar>=0.9.0',
-        'Flask-Login>=0.3.2',
         'simpleldap>=0.8',
         'simplekml>=1.2.3',
         'tornado>=4.0.2',