stack/erp5: add ghostscript to PATH of zopes

This will be used to do OCR from PDF documents
6 jobs for feat/tesseract-version-up in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.UnitTest-TesseractVersionUp

04:15:13

canceled ERP5.UnitTest-TesseractVersionUp

00:45:41

canceled ERP5.UnitTest-TesseractVersionUp

00:18:04

canceled ERP5.UnitTest-TesseractVersionUp

00:28:26

failed ERP5.UnitTest-TesseractVersionUp

04:20:50

failed ERP5.UnitTest-TesseractVersionUp

02:12:48