testing/corerad: upgrade to 1.2.1
Changelog: https://github.com/mdlayher/corerad/blob/main/CHANGELOG.md#v121
Signed-off-by: Mark Pashmfouroush mark@markpash.me
Changelog: https://github.com/mdlayher/corerad/blob/main/CHANGELOG.md#v121
Signed-off-by: Mark Pashmfouroush mark@markpash.me