How to make Fernet encryption produce the same ciphertext for the same data
It sounds like what you want is a deterministic authenticated cipher, or DAE, deterministic authenticated encryption, which has the property that an adversary can always tell when you have repeated messages, of course.

As far as I can tell, Fernet does not support any DAE.  Popular choices for DAE include SIV-type schemes like AES-SIV.  But you should have a good reason for using DAE first!  Most applications don't need it.