Edit a specific customer using a unique customer reference

put https://api-sandbox.modulrfinance.com/api-sandbox-token/customers/{customerId}

Currently editable fields:

For all customer types: externalReference can be edited
For all customers not requiring manual or in-house KYC verification: industryCode, registeredAddress, tcsVersions and regNumber can additionally be edited. Of those:
- For all other customer types: name and tradingAddress can additionally be edited
- For all types other than PCM_BUSINESS: the associate can additionally be edited