upgrade targetSdk to 33 and upgrade minSdk to 21, replace jcenter#336

maherelamary wants to merge 2 commits intolukasgit:masterlukasgit/flutter_contacts:masterfrom

maherelamary:fix/replace_jcenter_with_mavenCentralmaherelamary/flutter_contacts_package:fix/replace_jcenter_with_mavenCentralCopy head branch name to clipboard