fixed pylint bug and added channels redis to requirements

channel redis is needed for redis backend deployment

requirements.txt

@@ -8,4 +8,5 @@ django-auth-ldap==2.2.*
 qrcode==6.1
 latex==0.7.*
 django_prometheus==2.1.*
-channels==3.0.*
\ No newline at end of file
+channels==3.0.*
+channels-redis==3.2.*
\ No newline at end of file

requirements_dev.txt

 bandit==1.6.2
-pylint
+pylint==2.7.*
 pylint-django~=2.3.0
 django-stubs