Support urllib3 version 2

[adamchainz]

Is your feature request related to a problem? Please describe.

My project uses urllib3 version 2, released April 2023. Now I’m trying to add botbuilder to it, but it’s not possible because botbuilder-schema pins it to version <2:

botbuilder-python/libraries/botbuilder-schema/setup.py

Line 9 in a2cccb3

REQUIRES = ["msrest== 0.7.*", "urllib3<2.0.0"]

Commit 80b3572 did this.

It’s not exactly clear why though, because urllib3 isn't used directly anywhere.

Describe the solution you'd like

botbuilder-schema supports version 2 of urllib3. See migration guide.

Describe alternatives you've considered

Downgrading urllib3 but I have project code that uses v2-specific features.

Additional context
n/a