Fix FreeBSD CI

Author: Amanieu

.cirrus.yml

@@ -1,7 +1,7 @@
 task:
   name: x86_64-unknown-freebsd
   freebsd_instance:
-    image: freebsd-12-0-release-amd64
+    image: freebsd-12-1-release-amd64
   setup_script:
     - pkg install -y curl
     - curl https://sh.rustup.rs -sSf --output rustup.sh