create scheduled update of UMLS

[andrewsu]

UMLS is a key biomedical resource for diseases and other entities. http://mydisease.info/v1/metadata says the last update was April 2020. According to the release history, UMLS is updated twice a year every May and November. We should update UMLS to the latest version, and also have some sort of automated (or semi-automated) way to triggering these updates (or at least notifying a data manager). The relevant parser code is in https://github.com/biothings/mydisease.info/tree/master/src/plugins/umls.

Related issues:

• https://github.com/biothings/mygene.info/issues/124
• https://github.com/biothings/mychem.info/issues/130

[newgene]

2022AA is just released: https://www.nlm.nih.gov/research/umls/licensedcontent/umlsknowledgesources.html