leptonica download url changed

[anouar1991]

https://github.com/keensoft/alfresco-simple-ocr/blob/b789a5e0df19a9dde534e9b9e1f44deb0372c5e0/docker/pdfsandwich-1.6-centos-7/Dockerfile#L8

leptonica has moved from .com to org. which cause the current download link to produce an error while trying to extract the downloaded file:

tar zfxa leptonica-1.74.4.tar.gz

gzip: stdin: not in gzip format
tar: Child returned status 1
tar: Error is not recoverable: exiting now

because it is actually downloading an HTML page

# file leptonica-1.74.4.tar.gz
leptonica-1.74.4.tar.gz: HTML document, ASCII text

changing .com to .org will fix the problem http://www.leptonica.org/source/leptonica-1.74.4.tar.gz