Update get_rfi_mask to work with Python 3.11

[antrikshdhand]

This PR aims to allow developers to use the get_rfi_mask() function on Python 3.11. The rest of the code functionality is untouched. New developers should now be able to clone the repository, create a virtual environment, install the requirements listed in requirements-rfi.txt, and run example_rfi.py, which runs the SEEK SumThreshold algorithm on a spectrogram image.

This required a few changes to the code:

• Updating syntax to comply with modern NumPy and SciPy standards
• Removing the HOPE JIT compiler, as the project does not support Python >3.6
• Fixing a bug with the integer indexing in the author's original Gaussian filter function

[antrikshdhand]

• Fixed some matplotlib quirks to allow plots to appear sequentially
• Added some guard clauses to get_rfi_mask to prevent the running of mask dilation if mask=None
• Removed images from repository

[jakeret]

Hi Antriksh thanks for contributing. Do you want to merge this or is it still work in progress?

[antrikshdhand]

Hi Joel, no worries!

It should be good to merge. I haven't thoroughly tested the code, but I have only majorly changed the following files:

• seek/mitigation/sum_threshold.py
• seek/mitigation/sum_threshold_utils.py
  and added my own example file. The rest are syntax tweaks.

Thanks.