Fix details command after instrumentSuitability removal

[TiloHeidasch]

Closes #401

Trade Republic now rejects the instrumentSuitability WebSocket topic with BAD_SUBSCRIPTION_TYPE. The details output does not consume this response, so this removes the obsolete subscription and completes after the five remaining supported responses.

Verification:

• Reproduced the upstream rejection with an authenticated session.
• Verified the revised loop closes normally after five responses.
• Verified pytr details IE0000MR4GH9 retrieves instrument details against Trade Republic after the change.

[RealCLanger]

Looks correct, thanks for the contribution.

I also have some open work on the details command which includes this. But it's a good thing to merge this since my change is not quite ready yet.