Better documentation for normalization options

Spring cleaning. Fixed a bunch of packaging details and improved the README.rst page.

Info about normalization options is available. For example, help(miepython.i_per) will now tell you

i_per(m, x, mu, norm='albedo')
    Return the scattered intensity in a plane normal to the incident light.

    This is the scattered intensity in a plane that is perpendicular to the
    field of the incident plane wave. The intensity is normalized such
    that the integral of the unpolarized intensity over 4π steradians
    is equal to the single scattering albedo.

    The normalization is controlled by `norm` and should be one of
    ['albedo', 'one', '4pi', 'qext', 'qsca', 'bohren', or 'wiscombe']
    The normalization describes the integral of the scattering phase
    function over all 4𝜋 steradians.

    Args:
        m: the complex index of refraction of the sphere
        x: the size parameter of the sphere
        mu: the angles, cos(theta), to calculate intensities
        norm: (optional) string describing scattering function normalization

    Returns:
        The intensity at each angle in the array mu.  Units [1/sr]

2.5.4 (5/7/2024)

• document normalization in docstrings
• add version and year to CITATION.cff
• remove 'v' from version numbers
• add github script and workflow to auto-update CITATION.cff
• add conda badge to readme
• clean up README.rst
• use svg images
• use a single tests/test_mie for jit and non-jit tests
• support ruff
• test python versions 3.7 to 3.12
• fix badges
• remove unused functions
• fix zenodo link

Full Changelog: v2.5.3...2.5.4