SHA256 hashes instead of MD5

[TomazErjavec]

CLARIN.SI is currently undergoing CTS certification - one of the comments we received from the reviewers is:

"[Area of future investment] RDA guidance recommends SHA256 hashes over MD5 (both protect against bit-rot, but MD5 can technically be spoofed in a malicious attack). Given the low likelihood (and complexity) of such an attack, this isn't critical, but should be on the medium-term list of improvements."

Maybe something to consider.