Merge branch 'update-dependencies' into 'master'

Update dependencies

See merge request !83

requirements.txt

-Django==3.0.6
-django-bootstrap4==1.1.1
+Django==3.1.5
+django-bootstrap4==2.3.1
 django-fontawesome-5==1.0.18
 django-split-settings==1.0.1
-django-timezone-field==4.0
-djangorestframework==3.11.0
-django-simple-history==2.10.0
-django-registration-redux==2.8
+django-timezone-field==4.1.1
+djangorestframework==3.12.2
+django-simple-history==2.12.0
+django-registration-redux==2.9
 django-debug-toolbar==3.2
-mysqlclient==1.4.6  # for production deployment
+mysqlclient==2.0.3  # for production deployment