BinaryField value must be declared "binary" in queries to avoid MySQL 5.7+ warning

[Tim Graham]

There are a couple warnings with running the Django test suite on MySQL 5.7:

test_json_serializer (serializers.test_data.SerializerDataTests) ... /media/sf_django/django/db/backends/mysql/base.py:112: Warning: Invalid utf8 character string: 'FD00'
  return self.cursor.execute(query, args)

test_set_and_retrieve (model_fields.tests.BinaryFieldTests) ... /media/sf_django/django/db/backends/mysql/base.py:112: Warning: Invalid utf8 character string: 'FE'

I think these are both fixed by changing our queries from something like

cursor.execute("""
    INSERT INTO `field` (binary)
    VALUES (%s)
""", data)

to:

cursor.execute("""
    INSERT INTO `field` (binary)
    VALUES (_binary %s)
""", data)

The "_binary" tells MySQL that the following string is to be interpreted as binary, not to be interpreted/validated as utf8.
​http://dev.mysql.com/doc/refman/5.7/en/charset-literal.html

There's some background in #26139.

[Claude Paroz]

​PR

[Claude Paroz <claude@…>]

In 204e00c0:

Fixed #26140 -- Suppressed MySQL warning when inserting binary content

Thanks Tim Graham for the review.