Update urllib3 version constraint in recipe.yaml

[florentaden]

relax urllib3 pin from <=2.6.3 to <3 to fix PYSEC-2026-141/142 (#658)

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-admin]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe/recipe.yaml) and found it was in an excellent condition.

[xhochy]

This doesn't match upstream: https://github.com/aws/aws-cli/blob/12d962d239b9fd0669951c4d27dc366388abba2d/pyproject.toml#L47

[tkelman]

there's aws/aws-cli#10463 pending upstream, I'll keep an eye out for that getting merged since I had to disable greyskull for now