fix: remove return from finally block to resolve Python 3.14 SyntaxWa…

[Melissajwomack]

What does this PR do?

Removes return self.blocking_response from the finally block in _LambdaDecorator.__call__ and defers it to after the try/except/finally block, eliminating the SyntaxWarning: 'return' in a 'finally' block emitted by Python 3.14 at cold start.

Motivation

Python 3.14 introduced a SyntaxWarning for return/break/continue inside finally blocks because a return in finally silently suppresses any exception actively propagating through the try/except. This warning was firing on every Lambda cold start and polluting CloudWatch logs for anyone running on the Python 3.14 runtime.

Closes #758

Testing Guidelines

• Verified all four AppSec blocking execution paths remain correct (block before, block during via BlockingException, block after via _after, and normal/no-blocking)
• All existing unit tests in tests/test_wrapper.py, including TestLambdaWrapperAppsecBlocking, pass without modification
• Deployed to an AWS Lambda function running Python 3.14 — the SyntaxWarning no longer appears in CloudWatch logs at cold start

Additional Notes

The return in finally was originally needed so that when _after() sets self.blocking_response (the "block after response" AppSec path), that value could override the tentative return self.response from the try block. The fix preserves this behavior by deferring both returns to after the finally, using a simple if self.blocking_response check.

Types of Changes

• Bug fix

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