Fix Oklahoma registration date column name to get that data back

[cvcotton]

**Addresses issue(s): Oklahoma changed their registration date column name at some point in the past **

What this does

Manually changes the registration date column name back to the original name, so we can get the data into our schema.

Side effects

Should be none.

How to test

Process an Oklahoma file

Checklist

• This has been tested locally.
  • Notes:
• Commented code in a way that is useful for others.
  • Notes:
• Updated or created relevant documentation.
  • Notes:
• Added automated tests relevant to this new code.
  • Notes:

Other context

• Requires dependencies update: NO
• This is directly related to a pull request in another repo? YES
  • TBD in Inspector