fix(fallback): allow blank inputs for TeamMember comment field

shiftregister/fallback/models.py

@@ -20,7 +20,7 @@ def generate_id():
 class TeamMember(models.Model):
     id = models.IntegerField(default=generate_id, editable=False, primary_key=True)
     name = models.CharField(max_length=100)
-    comment = models.CharField(max_length=100, default="")
+    comment = models.CharField(max_length=100, blank=True, default="")
     fallback_shifts = models.ManyToManyField(Shift, through="FallbackAssignment")
 
     def url(self):