change Walgreens code to handle zip search

[cassjs]

Currently, the Walgreens link output sends a user to a page with a "Schedule new appointment Now" button, then the next page requests a zip. Will need to update the code to handle the zip being used when the application runs.

[VaccineWatcher] log  : Walgreens has Available Appointments: ['General'] for Next 5 in 77056, TX in 25 mile radius
Please Visit: https://www.walgreens.com/findcare/vaccination/covid-19?ban=covid_scheduler_brandstory_main_March2021 to schedule.