Fix return annotations and use staticmethod

aleksis/apps/kolego/schema/__init__.py

 from django.apps import apps
+from django.db.models import QuerySet
 
 import graphene
 import graphene_django_optimizer
@@ -31,10 +32,12 @@ class Query(graphene.ObjectType):
     absence_reason_tags = FilterOrderList(AbsenceReasonTagType)
     all_absence_reason_tags = FilterOrderList(AbsenceReasonTagType)
 
+    @staticmethod
     def resolve_app_name(root, info, **kwargs) -> str:
         return apps.get_app_config("kolego").verbose_name
 
-    def resolve_absences(root, info, **kwargs) -> str:
+    @staticmethod
+    def resolve_absences(root, info, **kwargs) -> QuerySet:
         return graphene_django_optimizer.query(
             get_objects_for_user(
                 info.context.user,
@@ -44,7 +47,8 @@ class Query(graphene.ObjectType):
             info,
         )
 
-    def resolve_absencereasons(root, info, **kwargs) -> str:
+    @staticmethod
+    def resolve_absencereasons(root, info, **kwargs) -> QuerySet:
         if not info.context.user.has_perm("kolego.fetch_absencereasons_rule"):
             return []
         return graphene_django_optimizer.query(
@@ -56,7 +60,8 @@ class Query(graphene.ObjectType):
             info,
         )
 
-    def resolve_absence_reason_tags(root, info, **kwargs):
+    @staticmethod
+    def resolve_absence_reason_tags(root, info, **kwargs) -> QuerySet:
         return graphene_django_optimizer.query(
             get_objects_for_user(
                 info.context.user,
@@ -66,7 +71,8 @@ class Query(graphene.ObjectType):
             info,
         )
 
-    def resolve_all_absence_reason_tags(root, info, **kwargs):
+    @staticmethod
+    def resolve_all_absence_reason_tags(root, info, **kwargs) -> QuerySet:
         return graphene_django_optimizer.query(
             get_objects_for_user(
                 info.context.user,