bump library version to 2.2.0

Bump com.android.billingclient library to v6.1.0

fix false condition in getSkuDetailsAsync

bump version for PurchaseInfo serialization fix

update version on readme

some more upgrading instructions

switch to SemVer. Bump build version to 1.1.0 to accomodate #414

bump build version to 45 to accomodate #315,#376,#411,#413

bump build version to accomodate #289, #293, #295

bump build version to accomodate #287