Fix UnboundLocalError masking RegistryError in gwinpy Registry.

Registry.RemoveKeyValue, SetKeyValue, GetRegKeys and GetRegKeysAndValues assigned handle inside a try block and closed it in finally. When _OpenSubKey failed (for example, the key does not exist), handle was never bound, so handle.Close() raised UnboundLocalError and replaced the original RegistryError. Callers that check RegistryError.errno (for example, treating errno 2 as “already absent”) never saw it.

Open the key before the try block, so a failed open propagates its RegistryError unchanged and finally only runs once a handle exists.

Add open-failure tests for all four methods, plus success and failure tests for RemoveKeyValue that check the handle is closed. Replace module-global monkeypatching in tests with mock.patch.object. Bump the version to 0.3.10.

PiperOrigin-RevId: 1004062859