[url_launcher] Replace deprecated RouteInformation APIs

[stuartmorgan]

Update for
https://docs.flutter.dev/release/breaking-changes/route-information-uri and makes 3.13 the minimum supported version accordingly.

Fixes flutter/flutter#124045

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[stuartmorgan]

This should be a no-op functionally, since the first non-assert code in the called method is uri ??= Uri.parse(location!); and that's the only use of location, so we're just doing the same thing the method would do with the deprecated param.

[ditman]

LGTM! Thanks for fixing this!!

(How did this surface? did we add some new lints, or did that SystemNavigatorApi get deprecated recently?)

[stuartmorgan]

It was surfaced at deprecation time by the deprecated_member_use lint; there's just no longer an annotation here due to #6123 and #6111

Now that we no longer have that lint, there's a manual process for tracking deprecations instead (at least for now; TBD if Flutter-wide tooling will be built), and so I'm doing a quick sprint to clean up the ones I can easily fix now to reduce the scope of the manual tracking.