cirrus: Temporarily fix libcurl link error

On FreeBSD the ftp/curl port appears to be missing a minimum
version dependency on libssh2, so the following starts showing
up after upgrading to curl 8.11.1_1:

  libcurl.so.4: Undefined symbol "libssh2_session_callback_set2"

Awaiting an upgrade of the FreeBSD CI images to version 14, work
around the issue.

Author: Jacob Champion <jacob.champion@enterprisedb.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://postgr.es/m/CAOYmi+kZAka0sdxCOBxsQc2ozEZGZKHWU_9nrPXg3sG1NJ-zJw@mail.gmail.com

Author: danielgustafsson

.cirrus.tasks.yml

@@ -168,6 +168,7 @@ task:
     sysctl kern.corefile='/tmp/cores/%N.%P.core'
   setup_additional_packages_script: |
     pkg install -y curl
+    pkg upgrade -y libssh2 # XXX shouldn't be necessary. revisit w/ FreeBSD 14
 
   # NB: Intentionally build without -Dllvm. The freebsd image size is already
   # large enough to make VM startup slow, and even without llvm freebsd