delete old dump before create

rsync-nextcloud/on_sbz_side/dump_all_databases.php

@@ -40,8 +40,12 @@ while ($row = mysqli_fetch_array($result)) {
 
 ## Zip all dumps
 $zipfile = "dumps.zip";
-$zip = new ZipArchive;
 
+if(file_exists($zipfile))
+{
+    unlink($zipfile);
+}
+$zip = new ZipArchive;
 if($zip -> open($zipfile, ZipArchive::CREATE ) === TRUE)
 {
     $dir = opendir($dumps_path);