Pytrimal

Changed
- Update vendored trimAl to `d89ffc3` (`2.0_RC`).
- Use `scoring-matrices` package to get a base for the `SimilarityMatrix` class.
- Rename `backend` to `platform` for all trimmer classes.
- Use trimAl platform-specific code to accelerate computations.
- Migrate documentation to `pydata-sphinx-theme`.

Fixed
- Missing trimmer classes in API documentation.
- Pin supported versions of `scoring-matrices` package to `~=0.2.0`.

Removed
- Outdated platform-specific code.
- `archspec` dependency (replaced by `cpu_features` used internally in trimAl).

Changed
- Bumped Cython dependency to `v3.0`.

Fixed
- Overflow in `calculateSpuriousVector` for certain sequence block sizes.
- MMX backend never being used unless explicitly required even when being the best supported backend.
Changed
- Use `archspec` Python package instead of `cpu-features` library for CPU feature detection at runtime.
- Use `importlib.resources.files` to load package data in `pytrimal.tests`.

Fixed
- `calculateSpuriousVector` method of SIMD implementations not being declared `override`.
Changed
- Replaced `aligned_alloc` with `posix_memalign` for compatibility with MacOS.

Added
- AVX2 and MMX implementations of the SIMD statistics computation.
- Tests for all SIMD implementations supported on the local machine.
Changed
- Refactor SIMD code using C++ templates and generic implementation.
Fixed
- Broken rendering of function signatures in Sphinx documentation.
- `residues_mask` and `sequences_mask` attributes of `TrimmedAlignment` not being documented ([1](https://github.com/althonos/pytrimal/issues/1)).

Fixed
- `SimilarityMatrix.nt` inverting the `degenerated` argument value.