Replace inspect.getargspec with inspect.getfullargspec (or possibly inspect.signature)

[kkaris]

inspect.getargspec is deprecated since 3.0(!), was removed in 3.11 and is replaced by inspect.getfullargspec. inspect.signature is also mentioned as the python 3 preferred way to deal with introspection, but inspect.getfullargspec seems to be safe from removal (for now) so easiest is to just replace it.

This affects the pipeline module: https://github.com/sorgerlab/indra/blob/master/indra/pipeline/pipeline.py#L323

See the Python 3.10 docs for the last version mentioning of inspect.getargspec:
https://docs.python.org/3.10/library/inspect.html#inspect.getargspec