Add version restruction to setup (#400)

Co-authored-by: Mark Gibbs <mark@gibbs.consulting>

Author: delsim

CONTRIBUTIONS.md

@@ -49,3 +49,5 @@ Thanks to the following people:
 [jmcarcell](https://github.com/jmcarcell)
 
 [gdalmau](https://github.com/gdalmau)
+
+[rosscg](https://github.com/rosscg)

setup.py

@@ -46,8 +46,13 @@
                         'dash-html-components',
                         'dash-renderer',
                         'dpd-components',
-                        'Django>=2.2',
-                        'Flask>=1.0.2'],
+
+                        'dash-bootstrap-components<1',
+                        'channels<3.0',
+                        'Django>=2.2,<4.0.0',
+                        'Flask>=1.0.2',
+                        'Werkzeug>=2.0,<2.1',
+    ],
     python_requires=">=3.6",
     )