Use branch alias instead of deployment ID in link

[dwhswenson]

It looks like pages-deployment-alias-url instead of deployment-url in the staging comment should do this:

https://github.com/cloudflare/wrangler-action/blob/707f63750981584eb6abc365a50d441516fb04b8/src/commandOutputParsing.ts#L64-L67

[dwhswenson]

Attempting to resolve in #10. We'll see if that worked.