functions: add zfs_release_duplicate_holds

scripts/zfs_release_duplicate_holds.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+for i in $(zfs get -Ht snapshot userrefs | grep -v $'\t'0 | cut -d $'\t' -f 1 | cut -f1 -d @ | uniq -d) ; do
+  for j in $(zfs list -H -t snapshot "$i" | awk '{ print $1 }') ; do
+    for k in $(zfs holds -H "$j") ; do
+      echo sudo zfs release syncoid_pbs "$k" | grep "@"
+    done
+  done
+done