fix(types): custom Awaited for TS 4.x

Fix #1006

packages/pinia/src/types.ts

@@ -165,7 +165,7 @@ type _Awaited<T> = T extends null | undefined
   ? T // special case for `null | undefined` when not in `--strictNullChecks` mode
   : T extends object & { then(onfulfilled: infer F): any } // `await` only unwraps object types with a callable `then`. Non-object types are not unwrapped
   ? F extends (value: infer V, ...args: any) => any // if the argument to `then` is callable, extracts the first argument
-    ? Awaited<V> // recursively unwrap the value
+    ? _Awaited<V> // recursively unwrap the value
     : never // the argument to `then` was not callable
   : T // non-object or non-thenable