move geckodriver.exe to SCRIPTS

[bollwyvl]

Checklist

• [x] Used a fork of the feedstock to propose changes
• [x] Bumped the build number (if the version is unchanged)
• [ ] Reset the build number to 0 (if the version changed)
• [x] Re-rendered with the latest conda-smithy
• [x] Ensured the license file is being packaged.

Windows build was ending up in %PREFIX%\bin%, which is not added to%PATH%` on activation!

[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.