need to update NCBI URLs

[deepakunni3]

All of the NCBI services have upgraded to using HTTPS but several of the URLs in the context JSON-LD are still using HTTP URL.

This results in no CURIE returned when contracting a URI using curie_util.contract_uri().

For example,

# URI with https yields no result
curie_util.contract_uri('https://www.ncbi.nlm.nih.gov/gene/9628')
[] 
# URI with http yields the correct CURIE
curie_util.contract_uri('http://www.ncbi.nlm.nih.gov/gene/9628')
['NCBIGene:9628']

But it's not clear ahead of time if all the incoming URIs are HTTP or HTTPS.

@cmungall

[deepakunni3]

This issue came up with monarch_context.jsonld.
Perhaps we have to update this JSON-LD every time Monarch makes a new release.