Fix up version constraints (#361)

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

.gitignore

@@ -88,6 +88,7 @@ celerybeat-schedule
 .venv
 venv/
 ENV/
+TOKENS
 
 # Spyder project settings
 .spyderproject

django_plotly_dash/version.py

@@ -23,4 +23,4 @@ SOFTWARE.
 
 '''
 
-__version__ = "1.6.5"
+__version__ = "1.6.6"

setup.py

@@ -41,7 +41,7 @@ setup(
     'Documentation': 'http://django-plotly-dash.readthedocs.io/',
     },
     install_requires = ['plotly',
-                        'dash>=1.11',
+                        'dash>=1.11,<1.21.0',
                         'dash-core-components',
                         'dash-html-components',
                         'dash-renderer',