getPurchaseHistory fails because an app is twice contained in the purchase history list

Hi, first of all thanks for your great work providing GPlayAPI.

On my Google account I ran into a problem with PurchaseHelper.getPurchaseHistory. Don't ask my why but my purchase history contains one app twice (may be I reposited that app and then bought it later again?).

And this leads to a server error when at the end of getPurchaseHistory AppDetailsHelper.getAppByPackageName is called.

Minimal reproducible example:

AppDetailsHelper appDetailsHelper = new AppDetailsHelper(authData);
appDetailsHelper.getAppByPackageName(List.of("com.teamspeak.ts3client", "com.teamspeak.ts3client"));

-> Server(code=500, reason=Internal Server Error)

The question is if the duplicate values should be filtered out in getPurchaseHistory or in getAppByPackageName.

BTW: I don't need all the app details when retrieving the purchase history (I only use packageName). Do you see a chance to modify getPurchaseHistory and for example add an optional Boolean argument that allows to bypass the mapping step using getAppByPackageName?

    fun getPurchaseHistory(offset: Int = 0, getAllAppDetails: Boolean = true): List<App> {
		....

        if (!getAllAppDetails)
            return purchaseAppList
        return AppDetailsHelper(authData).getAppByPackageName(purchaseAppList.map { it.packageName })
    }

If this would be acceptable I could provide a PR.