CI: Upgrade to FreeBSD 13.5

FreeBSD 13.5 was released on March 11, 2025:

https://www.freebsd.org/releases/13.5R/announce/

Author: neuschaefer

.cirrus.yml

@@ -12,10 +12,10 @@ task:
       env:
         TARGET: i686-unknown-freebsd
       freebsd_instance:
-        image_family: freebsd-13-4
+        image_family: freebsd-13-5
     - name: nightly freebsd-13 x86_64
       freebsd_instance:
-        image_family: freebsd-13-4
+        image_family: freebsd-13-5
     - name: nightly freebsd-14 x86_64
       freebsd_instance:
         image: freebsd-14-3-release-amd64-ufs