Pin numpy version to prevent further upgrade problems

[ruanslv]

Numpy 1.24.0 deprecated np.float, causing metaseq to throw errors: https://numpy.org/doc/stable/release/1.24.0-notes.html#expired-deprecations

Given the number of bytes in the map I'm assuming we meant float32 here, even though np.float actually used 8 bytes instead of 4...