upgrade dependencies

upgrade to django 3, closes #32
upgrade django-fontawesome-5

requirements.txt

-Django==2.2.6
+Django==3.0.6
 django-bootstrap4==1.1.1
-django-fontawesome-5==1.0.16
+django-fontawesome-5==1.0.18
 django-split-settings==1.0.1
 django-timezone-field==4.0
 djangorestframework==3.11.0