Numbers now allowed in DID Resolution Metadata -- test suite needs to allow that

[swcurran]

The test suite currently checks for an produces an error when there is a metadata attribute value that is a number. That is because the DID Resolution spec previously did not allow numbers in metadata. That was recently changed, and numbers are now allowed, with a caution to implementers to avoid numbers that are problematic in JSON -- e.g. larger than 32 bits. See this PR https://github.com/w3c/did-resolution/pull/180.

The spec references Section 7.3 of DID Core 1.0, but the DID Resolution metadata part of the spec is removed in DID Core 1.1 and moved to DID Resolution.

The test should be removed from the spec, allowing DID metadata with permitted numbers to be used.

I suppose a check that looks for a number that is not permitted might be added, but that will be tricky given the JSON data being processed...