Updated the FirebaseCore version.

Author: ryanwilson

FirebaseCore.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseCore'
-  s.version          = '5.2.1'
+  s.version          = '5.3.0'
   s.summary          = 'Firebase Core for iOS (plus community support for macOS and tvOS)'
 
   s.description      = <<-DESC

Releases/Manifests/5.17.0.json

@@ -1,7 +1,7 @@
 {
   "FirebaseAnalyticsInterop":"1.2.0",
   "FirebaseAuth":"5.3.1",
-  "FirebaseCore":"5.2.1",
+  "FirebaseCore":"5.3.0",
   "FirebaseFirestore":"1.0.1",
   "FirebaseFunctions":"2.2.1",
   "FirebaseInAppMessaging":"0.13.0",