Add event model stub from TIC-Desk

https://edugit.org/Teckids/ticdesk/-/blob/087d9e69d2f3e38225dff91c4ffae2c58c72a806/aleksis/apps/ticdesk/models.py

aleksis/apps/paweljong/models.py

+from django.db import models
+
+from aleksis.core.mixins import ExtensibleModel
+from aleksis.core.models import Group
+
+
+class Event(ExtensibleModel):
+    # Event details
+    display_name = models.CharField(verbose_name=_("Display name"), max_length=255, default="")
+    short_name = models.CharField(verbose_name=_("Short name"), max_length=255, default="")
+    group = models.ForeignKey(
+        Group, on_delete=models.CASCADE, verbose_name=_("Group"), related_name="event"
+    )
+    description = models.CharField(max_length=500, verbose_name=_("Description"))
+    published = models.BooleanField(default=False, verbose_name=_("Publish"))
+    place = models.CharField(max_length=50, verbose_name="Place")
+
+    # Date details
+    date_event = models.DateField(verbose_name=_("Date of event"))
+    date_registration = models.DateField(verbose_name=_("Registration deadline"))
+    date_retraction = models.DateField(verbose_name=_("Retraction deadline"))
+
+    # Other details
+    cost = models.IntegerField(verbose_name=_("Cost in €"))
+    max_participants = models.IntegerField(verbose_name=_("Max participants"))