Fix pip install -r requirements-dev.txt invocations

[kurtmckee]

I checked out the repository and attempted to install the dev requirements, but had two errors:

ERROR: Could not find a version that satisfies the requirement pyqt (from versions: none)
ERROR: No matching distribution found for pyqt

When attempting to run ptychodus, I saw a warning that PyQT5 could not be imported:

[WARNING] ptychodus.__main__: PyQt5 not found.

After fixing that, I got this error:

  × No solution found when resolving dependencies:
  ╰─▶ Because python was not found in the package registry and you require python>=3.10, we can conclude that your requirements are unsatisfiable.

With these two items addressed, I was able to run pip install requirements-dev.txt and successfully launch ptychodus.