LimaCCDs: Deprecation warning to replace `tostring`

While i was playing with the simulator i have received that stuff.

No idea why it's the first time i notice that stuff.

It is produced by _image_2_data_array

/nobackup/lvalls1/valls/Software/miniconda3/envs/tomodemoenv/lib/python3.7/site-packages/Lima/Server/LimaCCDs.py:1874: DeprecationWarning: tostring() is deprecated. Use tobytes() instead.
  dataStr = dataheader + flatData.tostring()

I can patch that stuff if you like.