Avoid needing numpy before pip install

[woutdenolf]

(py38) denolf@lindenolf:~$ pip install fisx
Collecting fisx
  Using cached fisx-1.2.0.tar.gz (5.7 MB)
  Preparing metadata (setup.py) ... error
  error: subprocess-exited-with-error
  
  × python setup.py egg_info did not run successfully.
  │ exit code: 1
  ╰─> [6 lines of output]
      Traceback (most recent call last):
        File "<string>", line 2, in <module>
        File "<pip-setuptools-caller>", line 34, in <module>
        File "/tmp/pip-install-0801lihx/fisx_a061210d946a4e838698022373c18b14/setup.py", line 82, in <module>
          import numpy
      ModuleNotFoundError: No module named 'numpy'
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
error: metadata-generation-failed

× Encountered error while generating package metadata.
╰─> See above for output.

note: This is an issue with the package mentioned above, not pip.
hint: See above for details.