Fixed packaging issues

Author: Brandon Sneed

Package.swift

@@ -3,7 +3,7 @@ import PackageDescription
 
 let package = Package(
     name: "SegmentFirebase",
-    platforms: [.macOS(.v10_13), .iOS(.v10)],
+    platforms: [.iOS(.v10)],
     products: [.library(name: "SegmentFirebase", targets: ["SegmentFirebase"])],
     dependencies: [
       .package(name: "Segment", url: "https://github.com/segmentio/analytics-ios.git", from: "4.1.3"),

Segment-Firebase/Classes/SEGFirebaseIntegration.m

@@ -1,10 +1,10 @@
 #import "SEGFirebaseIntegration.h"
-@import Firebase;
+#include <Firebase/Firebase.h>
 
 #if defined(__has_include) && __has_include(<Analytics/SEGAnalytics.h>)
 #import <Analytics/SEGAnalyticsUtils.h>
 #else
-@import Segment;
+@impo rt Segment;
 #endif