BUG: Overgeneration of galaxies

[Fox-Davidson]

Description

Added an h_0^3 to the number density calculated for galaxies and their redshifts. This closes #576 .

Checklist

• [x] Follow the Contributor Guidelines
• [ ] Write unit tests
• [ ] Write documentation strings
• [x] Assign someone from your working team to review this pull request
• [ ] Assign someone from the infrastructure team to review this pull request

[philipp128]

Thanks, @Fox-Davidson could you also adapt the tests in skypy/galaxies/tests/test_redshift.py. Currently these tests are failing.

[Fox-Davidson]

Closed as failed. Will try again fixed.