update to 21.2.1 in podspec, plist, STPAPIClient and VERSION

Stripe.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name                           = 'Stripe'
-  s.version                        = '21.2.0'
+  s.version                        = '21.2.1'
   s.summary                        = 'Stripe is a web-based API for accepting payments online.'
   s.license                        = { :type => 'MIT', :file => 'LICENSE' }
   s.homepage                       = 'https://stripe.com/docs/mobile/ios'

Stripe/Info.plist

@@ -13,11 +13,11 @@
 	<key>CFBundlePackageType</key>
 	<string>FMWK</string>
 	<key>CFBundleShortVersionString</key>
-	<string>21.2.0</string>
+	<string>21.2.1</string>
 	<key>CFBundleSignature</key>
 	<string>????</string>
 	<key>CFBundleVersion</key>
-	<string>21.2.0</string>
+	<string>21.2.1</string>
 	<key>NSPrincipalClass</key>
 	<string></string>
 </dict>

Stripe/STPAPIClient.swift

@@ -17,7 +17,7 @@ import Stripe3DS2
 /// A client for making connections to the Stripe API.
 public class STPAPIClient: NSObject {
   /// The current version of this library.
-  @objc public static let STPSDKVersion = "21.2.0"
+  @objc public static let STPSDKVersion = "21.2.1"
 
   /// A shared singleton API client.
   /// By default, the SDK uses this instance to make API requests

VERSION

@@ -1 +1 @@
-21.2.0
+21.2.1