Fix iterators

[moble]

• Remove Logging from two places in main Project.toml
• Remove NullLogger occurrences from four places in test/iterators.jl
• Remove admonitions in D_iterator and d_iterator docstrings
• Remove iterator_warning from three places in src/iterators.jl
• Fix the problem
• Fix tests — both broken and working
• Close relevant issue (but not this one!) in commit messages
• Release new major version
• Add description of major changes to release message
• Close this issue manually

[AuroraDysis]

Hi @moble, thank you for developing this package. While your numerical method is optimal, I've found the interface to be a bit perplexing at times. I attempted to use the iterators, but encountered some bugs with the sYlm_iterator. I managed to find a workaround to use the package without it, which can be found here:
https://github.com/AuroraDysis/Einstein.jl/blob/4bd9de6c235772cd207797d641a7d3c2496d316d/src/utils/sws.jl#L256-L296
However, this solution isn't ideal for me.

For instance, I believe most users would appreciate a function for spin-weighted spherical harmonics with parameters (s, l, m, theta, phi) for testing purposes. Additionally, for the returned vector of sYlm_values!, it would be beneficial to provide functions like sYlm_idx(l, m) and sYlm_value(values, l, m) which provide the index and value for given l and m. These are just a few simple ideas, and you might have more elegant solutions. Do you have any plans to enhance this aspect?