Fix connectivity monitor redispatching. (#3665)

* Fix connectivity monitor redispatching.

In #3467, we changed the connectivity monitor to take callbacks from
SCNetworkReachability on the main thread but didn't make the
corresponding change to enqueue the notification back onto Firestore's
worker.

* Bump patch version

* CHANGELOG

Author: wilhuff

FirebaseFirestore.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FirebaseFirestore'
-  s.version          = '1.4.4'
+  s.version          = '1.4.5'
   s.summary          = 'Google Cloud Firestore for iOS'
 
   s.description      = <<-DESC

Firestore/CHANGELOG.md

@@ -1,5 +1,9 @@
 # Unreleased
 
+# v1.4.5
+- [fixed] Fixed a crash that would happen when changing networks or going from
+  online to offline. (#3661).
+
 # v1.4.4
 - [changed] Internal improvements.
 

Firestore/core/src/firebase/firestore/remote/connectivity_monitor_apple.mm

@@ -124,7 +124,7 @@ explicit ConnectivityMonitorApple(
   }
 
   void OnReachabilityChanged(SCNetworkReachabilityFlags flags) {
-    queue()->ExecuteBlocking(
+    queue()->Enqueue(
         [this, flags] { MaybeInvokeCallbacks(ToNetworkStatus(flags)); });
   }