Add support for bandpass integration

[0.7.0] - 2022-10-06

New

• Added support for bandpass integration. The get_*_emission_* methods now accept a sequence of frequencies to the freq argument and corresponding weights to the new weights argument.
• Add numba as a dependency.

Changed

• By default, ZodiPy will now run concurrently and spawn processes based on the number of available CPU's (given by os.cpu_count()). This can be turned off by initializing Zodipy with parallel=False. The number of CPUs can be manually specified by using the n_proc keyword when initializing ZodiPy.