component/tesseract: fix permissions of downloaded traineddata

With the default umask of running slapos node, the default umask create files
that are only readable by user, not by group:

    slapuser10@COMP-1234:~$ ls -al /opt/slapgrid/bf0ccebdbd76d491bcbe16b7998529b2/parts/tesseract/share/tessdata/
    total 125296
    drwxr-x--- 4 slapsoft slapsoft 4096 Jul 13 05:57 .
    drwxr-x--- 3 slapsoft slapsoft 4096 Jul 13 05:57 ..
    -rw------- 1 slapsoft slapsoft 44366093 Jul 13 05:57 chi_sim.traineddata
    drwxr-x--- 2 slapsoft slapsoft 4096 Jul 13 05:57 configs
    -rw------- 1 slapsoft slapsoft 23466654 Jul 13 05:57 eng.traineddata
    -rw------- 1 slapsoft slapsoft 14213351 Jul 13 05:57 fra.traineddata
    -rw------- 1 slapsoft slapsoft 35659159 Jul 13 05:57 jpn.traineddata
    -rw------- 1 slapsoft slapsoft 10562874 Jul 13 05:57 osd.traineddata
    -rw-r--r-- 1 slapsoft slapsoft 572 Jul 13 05:57 pdf.ttf
    drwxr-x--- 2 slapsoft slapsoft 4096 Jul 13 05:57 tessconfigs

but when using multiple users, partitions users are members of slapsoft group,
so these files needs to be group readable.

component/tesseract/buildout.hash.cfg

 [download-tessdata.py]
 filename = download-tessdata.py
-md5sum = 2d283a6d8662d6bb8c9de7b26162b702
+md5sum = 1f6cf2797f0daf9dec16c1d3a8c44907

component/tesseract/download-tessdata.py

@@ -19,9 +19,13 @@ def post_make_hook(options, buildout, env):
   for url in options['tessdata-urls'].splitlines():
     url, _, md5sum = url.partition('#')
     if url:
+      destination = os.path.join(
+          options['tessdata-location'],
+          os.path.basename(url),
+      )
       download(
           url,
           md5sum=md5sum,
-          path=os.path.join(options['tessdata-location'],
-                            os.path.basename(url)),
+          path=destination,
       )
+      os.chmod(destination, 0o750)