pipdeptree does not handle extras

[sapols]

E.g. if you try to get pipdeptree output for pyhc-core[tests], the [tests] part breaks it and we get empty output, which breaks the pipeline.

The temporary fix is to simply modify get-dep-tree-for-package.sh to ignore the [extra] part when it's present, but this means the resulting dependency spreadsheet will not contain any info about those extra dependencies. Meaning the spreadsheet would technically be incomplete and there could be a dependency conflict from the extras that we wouldn't detect.

[sapols]

Found an issue about this in their GitHub: tox-dev/pipdeptree#107
(Seems some started working on it a few years ago, then stopped, and it's been back burnered since)