fixed warnings in models

marktplatz/models.py

@@ -159,7 +159,7 @@ class Product(models.Model):
     rechtsform      = CharField   ( 'Rechtsform', max_length = 32, help_text="Rechtsform des Projektes", null = True, blank=True )
     orga            = CharField   ( 'Organisationsform',  max_length = 256, help_text="Organisationsform des Projektes.", null = True, blank=True )
     mitmachen       = BooleanField( 'Mitmachen möglich', default=False, help_text="Kann jemand mitmachen?", blank=False )
-    terms           = NullBooleanField(help_text="")
+    terms           = BooleanField(help_text="", null=True)
     edit            = BooleanField( default=True, help_text="", blank=False )
     public          = BooleanField( default=False, help_text="", blank=False )
     contact         = ForeignKey(Contact, null = True,on_delete=models.SET_NULL, help_text="")
@@ -180,7 +180,7 @@ class Product(models.Model):
 
     photo = CharField(max_length=500, null=True, blank=True, help_text="")
     videocts = CharField(max_length=500, null=True, blank=True, help_text="")
-    category = ManyToManyField(Category,  help_text="",null = True, blank=True)
+    # category = ManyToManyField(Category,  help_text="",null = True, blank=True)
     # credits = ForeignKey(Credit, null = True, blank=True, on_delete=models.SET_NULL, help_text="")
     #interaction = ForeignKey(Interaction, null = True,on_delete = models.SET_NULL, help_text="")