Bump promises dependency (#31)

* Bump promises dependency

* Fix podspec

* Include Promises in Package.swift

* Bump Promises in Package.swift

* Bump podspec minor version

* CHANGELOG

* Bump to 9.1.0

* Fix CHANGELOG

GoogleDataTransport.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'GoogleDataTransport'
-  s.version          = '9.0.1'
+  s.version          = '9.1.0'
   s.summary          = 'Google iOS SDK data transport.'
 
   s.description      = <<-DESC
@@ -41,7 +41,7 @@ Shared library for iOS SDK data transport needs.
 
   s.dependency 'GoogleUtilities/Environment', '~> 7.2'
   s.dependency 'nanopb', '~> 2.30908.0'
-  s.dependency 'PromisesObjC', '~> 1.2'
+  s.dependency 'PromisesObjC', '>= 1.2', '< 3.0'
 
   header_search_paths = {
     'HEADER_SEARCH_PATHS' => '"${PODS_TARGET_SRCROOT}/"'