Primer3-py

- Fix `_ThermoAnalysis._set_globals_and_seq_args` for improper checks on `misprime_lib` and
`mishyb_lib` leading to incorrect initialization of `mp_lib` and `mh_lib`. See issue 133

- Support for python 3.12 (build, test, docs)

- Fixed bug in `todict` method of `ThermoAnalysis`

- Migrated primer3 header file Cython extern imports to `thermoanalysis.pxi`
- Optional C structure string argument `c_ascii_structure` added to `_ThermoAnalysis` methods to enable 3rd party use for structures
- Version bump to 2.0.0 due to breaking change
- Fix issue whereby no_structure is not correctly 1 set to 1 when no secondary structure in found
- Add list version of `PRIMER_{PAIR, LEFT, RIGHT, INTERNAL}` to design output dictionary keys. Retaining original keys as well for compatibility.
- Fix for missing `thal_result.sec_struct` and `dpal_results.sec_struct` initialization to `NULL` in `recalc_primer_sec_struct`

- Bug fixes for output formatting related to penalty, "problem", and mispriming fields

- Bug fixes for `pdh_create_seq_lib` to correct missing `seq_lib` datastructure allocation and variable name typos.
- Increase test coverage to include `misprime_lib` and `mishyb_lib` arguments