ci: Document why tests can not be run on mac
ci: Document why tests can not be run on mac

Former-commit-id: 0117fe78b24f630bcf225e687bf1542109dfe2a4
syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin