Update Windows activation to use VS2019

[pkgw]

Inspired by conda-forge/cryptography-feedstock#104 and my reading of conda-forge/conda-forge.github.io#1732, I think the Rust activation packages on Windows need updating to stay in sync with the VS2019 bump.

xref conda-forge/conda-forge-pinning-feedstock#3167 xref conda-forge/conda-forge.github.io#1810

CC @h-vetinari

Checklist

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

[conda-forge-linter]

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) and found it was in an excellent condition.

[github-actions[bot]]

Hi! This is the friendly conda-forge automerge bot!

I considered the following status checks when analyzing this PR:

• linter: passed
• azure: passed

Thus the PR was passing and merged! Have a great day!