(hyperion#1307) change DetectorParams detector_size_constants validator to allow the declared type

[rtuck99]

Change to address PR comment in DiamondLightSource/hyperion#1307

Instructions to reviewer on how to test:

Tests pass

Checks for reviewer

• Would the PR title make sense to a scientist on a set of release notes
• If a new device has been added does it follow the standards
• If changing the API for a pre-existing device, ensure that any beamlines using this device have updated their Bluesky plans accordingly
• Have the connection tests for the relevant beamline(s) been run via dodal connect ${BEAMLINE}

[DominicOram]

Great, thanks. No one other than i03 is using this so we don't necessarily need to keep both behaviours, I think it's not too much overhead to keep for now though