NumPy deprecation warning

[cnavacch]

This issue causes a warning with Python==3.7 and numpy==1.20 at the moment:

...\lib\site-packages\equi7grid\equi7grid.py:567: DeprecationWarning: `np.int` is a deprecated alias for the builtin `int`. To silence this warning, use `int` by itself. Doing this will not modify any behavior and is safe. 
When replacing `np.int`, you may wish to use e.g. `np.int64` or `np.int32` to specify the precision. If you wish to review your current use, check the release note link for additional information.
  Deprecated in NumPy 1.20; for more details and guidance: https://numpy.org/devdocs/release/1.20.0-notes.html#deprecations
    np.int(llx) // 100000, np.int(lly) // 100000, tilecode)