Replace EOTK repository URL with Onionspray's

EOTK was forked, and this commit updates it's URL to the new location.

All links pointing to EOTK were updated, except for this one which seems an old and disabled archive post: https://gitlab.torproject.org/tpo/web/community/-/blob/main/content/gsoc/archive/onion-toolbox/contents.lr?

Details tpo/onion-services/eotk#1.

Closes #337 (closed).