chore: add missing 'is_anonymous' property to User type (#871)

## What kind of change does this PR introduce?

Types update

## What is the current behavior?

User type is missing 'is_anonymous' property.

## What is the new behavior?

User type has the 'is_anonymous' property.

## Additional context

I'm not 100% certain if this property is optional or not, hoping
@kangmingtay can offer some insight as they implemented the feature in
supabase/auth#68

Fixes #872

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Co-authored-by: Kang Ming <[email protected]>

src/lib/types.ts

@@ -339,6 +339,7 @@ export interface User {
   role?: string
   updated_at?: string
   identities?: UserIdentity[]
+  is_anonymous?: boolean
   factors?: Factor[]
 }