🧪 test: edge case tests for string error-codes

[rowan-m]

🎯 What: The testing gap addressed was testing the edge cases of the error-codes parameter in ReCaptcha\Response when an API response accidentally provides a non-array value like a string, integer, or null.
📊 Coverage: The scenarios now tested in ResponseTest::provideJson include string error codes, null error codes, and integer error codes.
✨ Result: Test coverage for src/ReCaptcha/Response.php remains at 100%, but the edge case behavior of defaulting to ReCaptcha::E_UNKNOWN_ERROR is properly verified for more invalid API inputs.

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PR created automatically by Jules for task 3707114257801985178 started by @rowan-m

[google-labs-jules]

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[coveralls]

coverage: 100.0%. remained the same
when pulling 416d864 on jules-testing-improvement-error-codes-3707114257801985178
into 6b49254 on main.