fix(types): workaround for popper weak type

Fixes #644

src/runtime/types/popper.d.ts

@@ -1,6 +1,8 @@
 import type { Placement, PositioningStrategy } from '@popperjs/core'
 
 export interface PopperOptions {
+  // Workaround for weak types: https://mariusschulz.com/blog/weak-type-detection-in-typescript#workarounds-for-weak-types
+  [key: string]: unknown
   locked?: boolean
   overflowPadding?: number
   offsetDistance?: number