fix: use appleid.apple.com as default issuer (#2068)

## What kind of change does this PR introduce?

Bug fix

## What is the current behavior?

Sign-in with Apple does not open the native sign-in flow (face-id +
"continue" button), but rather redirects to the account.apple.com
website, where users have to do a full manual sign-in. I'm pretty sure
this is due to a change introduced (the change to using
"account.apple.com" instead of "appleid.apple.com") while there was an
outage/issue on Apple's side.

## What is the new behavior?

The native sign-in flow should be used when available (e.g. on an iOS
device).

## Additional context

This should resolve the problem described by [lizbzlx
(comment)](#2051 (comment)),
[obeliskgroup
(comment)](#2051 (comment))
and [bsheikh
(comment)](#2051 (comment))
in [this issue](#2051).

Author: korkje

internal/api/provider/apple.go

@@ -15,8 +15,8 @@ import (
 	"golang.org/x/oauth2"
 )
 
-const DefaultAppleIssuer = "https://account.apple.com"
-const OtherAppleIssuer = "https://appleid.apple.com"
+const DefaultAppleIssuer = "https://appleid.apple.com"
+const OtherAppleIssuer = "https://account.apple.com"
 
 func IsAppleIssuer(issuer string) bool {
 	return issuer == DefaultAppleIssuer || issuer == OtherAppleIssuer