fix: [rsync-backup-target] allow adding ssh keys from latest version of openssh

rsync-backup-target/build/src/usr/local/sbin/ssh-admin-cmd-validate

@@ -44,7 +44,7 @@ if [[ "$SSH_ORIGINAL_COMMAND" =~ [\&\(\{\;\<\>\`\$\}] ]]; then
     reject
 fi
 
-if [[ "$SSH_ORIGINAL_COMMAND" =~ ^"ssh-key add ssh-rsa "[a-zA-Z0-9/+]+" "[a-zA-Z0-9._-]+"@"[a-zA-Z0-9._-]+""$ ]]; then
+if [[ "$SSH_ORIGINAL_COMMAND" =~ ^"ssh-key add ssh-rsa "[a-zA-Z0-9/+=]+" "[a-zA-Z0-9._-]+"@"[a-zA-Z0-9._-]+""$ ]]; then
 	log "ACCEPTED: $SSH_ORIGINAL_COMMAND"
 
     ## Interpret \ to allow passing spaces (want to avoid possible issue with \n)