[stubsabot] Bump braintree to 4.39.*

Release: https://pypi.org/pypi/braintree/4.39.0
Homepage: https://developer.paypal.com/braintree/docs/reference/overview
Repository: https://github.com/braintree/braintree_python
Typeshed stubs: https://github.com/python/typeshed/tree/main/stubs/braintree
Diff: braintree/braintree_python@4.38.0...4.39.0

Stubsabot analysis of the diff between the two releases:
 - 6 public Python files have been added: `braintree/bank_account_instant_verification_gateway.py`, `braintree/bank_account_instant_verification_jwt.py`, `braintree/bank_account_instant_verification_jwt_request.py`, `braintree/receiver.py`, `braintree/sender.py`, `braintree/transaction_us_bank_account_request.py`.
 - 0 files included in typeshed's stubs have been deleted.
 - 8 files included in typeshed's stubs have been modified or renamed.
 - Total lines of Python code added: 946.
 - Total lines of Python code deleted: 12.

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Author: stubsabot

stubs/braintree/METADATA.toml

@@ -1,2 +1,2 @@
-version = "4.38.*"
+version = "4.39.*"
 upstream_repository = "https://github.com/braintree/braintree_python"