release: bump FirebaseCore.podspec and Package.swift versions for patch release

Author: ncooke3

FirebaseCore.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseCore'
-  s.version          = '12.12.0'
+  s.version          = '12.12.1'
   s.summary          = 'Firebase Core'
 
   s.description      = <<-DESC

Package.swift

@@ -18,7 +18,7 @@
 
 import PackageDescription
 
-let firebaseVersion = "12.12.0"
+let firebaseVersion = "12.12.1"
 
 let shouldUseSourceFirestore = Context.environment["FIREBASE_SOURCE_FIRESTORE"] != nil