Fix GetOverride response schema length mismatch

[gruijter]

Problem

The current schema for the GetOverride responseType specifies:

• action: uint8 (1 byte)
• startTime: tUnixTime (4 bytes)
• duration: uint32 (4 bytes)

This expects a total payload size of 9 bytes. However, Husqvarna/Gardena mowers consistently return 13 bytes for this command. This leads to a decoding failure with the exception:
ValueError: Data length mismatch. Read 9 bytes of 13

Solution

Manual decoding shows that the first 9 bytes contain correct values (action, startTime, and duration are decoded perfectly), leaving a trailing 4-byte chunk. This PR adds an unknown: uint32 field to the GetOverride responseType schema to match the 13 bytes returned by mowers.

Verification

A unit test test_decode_get_override_response was added to tests/test_response.py to verify that a 13-byte response for GetOverride decodes correctly.

[gruijter]

Note: this may overlap with #148 — happy to close/rebase once that lands, whichever the maintainer prefers.

[AlirezaT]

I checked this against #148. This specific GetOverride length mismatch should already be covered there.

#148 changes the trailing GetOverride response field to reserved: remaining_uint, so the known 13-byte response parses without forcing a fixed trailing uint32, and it also remains tolerant if mower variants return a different amount of trailing/reserved data.

So if #148 lands first, this PR is probably redundant, though the unit test here is still useful evidence for the 13-byte response.