Fix: fix constraint creation using the wrong table and column name

[BlueMagma2]

Subject: Fix a bug regarding foreign key constraint creation

Feature or Bugfix

• Bugfix

Detail

• This was causing issue if a foreign key was pointing to another field than the remote table id

eg.

Table1(models.Model):
    remote_column = models.IntegerField(unique=True)

Table2(models.Model):
    local_column = models.ForeignKey(to=Table1, to_field='remote_column')

During the migrations, you would get an error saying Table2 doesn't have a column named remote_column which is absurd since that colum is not supposed to be in that table.

[BlueMagma2]

@shimizukawa I see you merged the last PR, though I admit it was some time ago. Can you have a look ?

PS: I apologise for pinging you if you are the wrong person to address this

[shimizukawa]

LGTM!

@BlueMagma2 I'm sorry for the late confirmation.
I created a another PR #139 to resolve conflict and adding tests.
Thanks for your contribution!

[BlueMagma2]

Ha cool, I'm happy to see this was merged, thanks you