v3.0.0-beta-3

Summary:
This (pre-)release adds a transition guide for users who worked with prior versions of pyTMD and a couple of small fixes for paths and urls.

Itemized Changes:

• fix: expanduser on local paths by (#496)
• docs: add transition guide for v3 (#497)
• docs: add reference to v3 release notes (#498)
• docs: add currents to transition guide (#499)
• feat: add name, stem and parent to URL class (#500)
• docs: add reference to TMD2.5 (#501)

Full Changelog: 3.0.0-beta-2...3.0.0-beta-3