migrate: replace deprecated output: server refrence with SSR

[Keshav-writes-code]

as of astro 5, the output: server is optional and not needed

Description (required)

So, the firebase and astro getting started documentation says that you need a astro project with config output: "server" which is no longer needed as of astro 5. so removing it to not cause any confusion for future readers

Just replaced the output:"server" refrence in the top of the document to point to "SSR" enabled project instead

discord: gdm_music

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[sarah11918]

Hi Keshav! Thank you for finding this one... we've been trying to "catch them all" and replace them, but some keep slipping through. 😄

One issue with making this change, though, is that the rest of the page assumes output: 'server' and therefore this guide would not work as intended without it.

All the routes would be server-rendered by default in this guide, so you would never need to say export const prerender = false to make this guide work. If you remove the server requirement, then this whole page needs to be checked and the line of code to prevent prerendering needs to be added to all the example files that do need to be server rendered.

So, if you'd like to continue with this change (which I think is a good one!), then you'll need to check the entire guide carefully, because it was written specifically for output: 'server' and this entire guide assumes routes will NOT be prerendered by default. Are you still interested in continuing with this?