species v0.9.0

• Added support for Python 3.12, dropped support for Python 3.9
• Separated atmosphere and disk luminosity in ModelBox parameters
• Fixed issue with finding missing grid spectra
• Fixed issue with plotting filter profile width
• Added pyproject.toml and removed setup.py
• Removed most version restrictions from requirements.txt
• Added font_size parameter to plot_spectrum
• Fixed pathlib error when adding grids with add_custom_model
• Updated flux calibration tutorial
• Many small improvements and overall code maintenance