community/rnp: upgrade to 0.16.2

Thunderbird still patches rnp to disable some obsolete ciphers, but
since was merged, MD5/SHA1 are
disabled by default for signature verification, so it shouldn't be so
important to justify maintaining a complicated patch.
9 jobs for !41568 with rnp in 9 minutes and 32 seconds (queued for 2 seconds)
latest merge request