Fix error running tesseract_exec engine

It couldn't find the output file ..

16:23:58.337409 OCR_TESSERACT: cmdArgs: [/tmp/05325563-e110-4dfe-593f-83a97daae019 /tmp/928e15d3-7b39-4d0b-447a-98b8d00c6fd8 -c tessedit_char_whitelist=0123456789 -psm 0]
16:23:59.146967 OCR_TESSERACT: Error getting data from out file: open /tmp/928e15d3-7b39-4d0b-447a-98b8d00c6fd8.txt: no such file or directory