Add default None to optional fields

[0e4ef622]

for pydantic v2

---

Note

Medium Risk
Touches many Pydantic response/request models; while changes are largely default-value semantics, they can affect validation/requiredness and serialized output in client integrations.

Overview
Bumps the SDK version to 5.4.0.

Updates multiple Pydantic models (e.g., bank statements, entities, reports, recurring payments, income check, webhooks, recurrence groups) to set explicit = None defaults for Optional[...] fields, aligning model required/optional behavior with Pydantic v2 expectations. A v2 bank statement test fixture ID is also updated.

^{Reviewed by Cursor Bugbot for commit edb677b. Bugbot is set up for automated code reviews on this repo. Configure here.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit ed5a062. Configure here.}