Remove unused code

pdf-sign

@@ -2,7 +2,7 @@
 
 #Dependencies: python3, pdftk, gs, mv, pdfinfo
 
-import argparse, os, queue, re, subprocess, sys, tempfile, threading, time
+import argparse, os, queue, re, subprocess, sys, tempfile, time
 
 signatureDir=os.path.expanduser(os.environ['PDF_SIGNATURE_DIR'] if 'PDF_SIGNATURE_DIR' in os.environ else "~/.pdf_signatures")