fix: type declarations don’t depend on internal typings (#129)

We prevent typescript from generating declarations that reference the
`@paypal/sdk-constants` package. This package does not provide types,
instead we use our own type declarations in `./src/types.d.ts`. These
declarations are not available to users of the library.

Fixes #125

src/index.ts

@@ -3,4 +3,10 @@ export * from "./components/PayPalMarks";
 export * from "./components/PayPalMessages";
 export * from "./ScriptContext";
 
-export { FUNDING } from "@paypal/sdk-constants/dist/module";
+import * as constants from "@paypal/sdk-constants/dist/module";
+
+// We do not re-export `FUNDING` from the `sdk-constants` module
+// directly because it has no type definitions.
+//
+// See https://github.com/paypal/react-paypal-js/issues/125
+export const FUNDING: Record<string, string> = constants.FUNDING;