www/node12: Update 12.14.1 -> 12.15.0

https://nodejs.org/en/blog/release/v12.15.0/

This is a security release. See
https://nodejs.org/en/blog/vulnerability/february-2020-security-releases/

MFH: 2020Q1
Security: 0032400f-624f-11ea-b495-000d3ab229d6
Sponsored by: Miles AS