requirements.txt pinned to legacy versions of libraries

[sooslaca]

Describe the bug

Same as #581

Expected behavior

Be able to use latest version of xmltodict, as of today https://github.com/martinblech/xmltodict/releases/tag/v1.0.2

Current behavior

Cannot install other galaxy modules as palo is using legacy xmltodict version

Possible solution

Update requirements.txt

Steps to reproduce

1. Add galaxy module eg: azure.azcollection
2. Add galaxy module paloaltonetworks.panos