-Wno-deprecated-declarations is needed because of OpenSSL 3 (and macos stupidly deprecating daemon(3) in favour of that trash of posix_spawn.)

the runtime tests fails on the ci (gg: Connection refused); will be revisited after we get a real `listen on' directive.

Add a cirrus CI config file that runs the regression suite on linux amd64/aarch64 and on freebsd.