Add SPM support (#223)

* Add SPM support

* Cleanup cocoapods bits from example app

* Update package references for universal-ble in Xcode project

* Refactor notification handling and error logging in UniversalBleWeb class

* Change min sdk version

* Update CHANGELOG.md to include SPM support on Apple and requestConnectionPriority feature for version 1.3.0

darwin/universal_ble.podspec

@@ -13,7 +13,7 @@ A new Flutter plugin project.
   s.license          = { :file => '../LICENSE' }
   s.author           = { 'Your Company' => 'email@example.com' }
   s.source           = { :path => '.' }
-  s.source_files = 'Classes/**/*'
+  s.source_files = 'universal_ble/Sources/universal_ble/**/*.swift'
   s.ios.dependency 'Flutter'
   s.osx.dependency 'FlutterMacOS'
   s.ios.deployment_target = '13.1'
@@ -21,5 +21,5 @@ A new Flutter plugin project.
 
   # Flutter.framework does not contain a i386 slice.
   s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES', 'EXCLUDED_ARCHS[sdk=iphonesimulator*]' => 'i386' }
-  s.swift_version = '5.0'
+  s.swift_version = '5.9'
 end