Use stringified version in Package.swift

should prevent deprecation warning

Author: futuretap

FTLinearActivityIndicator.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'FTLinearActivityIndicator'
-  s.version          = '1.5'
+  s.version          = '1.5.2'
   s.summary          = 'Add the missing network activity indicator on iPhone with notch'
 
   s.description      = <<-DESC

Package.swift

@@ -6,7 +6,7 @@ import PackageDescription
 let package = Package(
     name: "FTLinearActivityIndicator",
     platforms: [
-        .iOS(.v9)
+        .iOS("9.0")
     ],
     products: [
         // Products define the executables and libraries produced by a package, and make them visible to other packages.