Upgrade django-helusers to v0.5.5

This fixes admin UI logout which was broken.

Author: tuomas777

requirements.txt

@@ -11,7 +11,7 @@ django-anymail==7.0.0     # via django-ilmoitin
 django-cors-headers==3.1.1
 django-environ==0.4.5
 django-graphql-jwt==0.2.2
-django-helusers==0.5.2
+django-helusers==0.5.5
 django-ilmoitin==0.3.0
 django-mailer==2.0        # via django-ilmoitin
 django-parler==1.9.2