cache Growl installer on AppVeyor

[refack]

Requirements

• Filling out the template is required. Any pull request that does not include enough information to be reviewed in a timely manner may be closed at the maintainers' discretion.
• All new code requires tests to ensure against regressions.

Description of the Change

Alternate Designs

Why should this be in core?

Benefits

Possible Drawbacks

Applicable issues

Fixes #4390

[jsf-clabot]

Thank you for your submission, we really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

[boneskull]

@refack can you do the CLA dance pls?

[boneskull]

@outsideris can you use this strategy in #4402 ?

[outsideris]

@boneskull I didn't install Growl on Windows because the tests seem not affected by the installation. I will check it again.

[outsideris]

Sorry, we moved it to GitHub Actions.