Update the Podspec for v0.10, with gRPC-Core 1.23 and Swift 5. (#612)

SwiftGRPC.podspec

@@ -11,7 +11,7 @@
 
 Pod::Spec.new do |s|
   s.name = 'SwiftGRPC'
-  s.version = '0.9.1'
+  s.version = '0.10.0'
   s.license     = { :type => 'Apache License, Version 2.0',
                     :text => <<-LICENSE
                       Copyright 2018, gRPC Authors. All rights reserved.
@@ -32,7 +32,7 @@ Pod::Spec.new do |s|
   s.authors  = { 'The gRPC contributors' => 'grpc-packages@google.com' }
   s.source = { :git => 'https://github.com/grpc/grpc-swift.git', :tag => s.version }
 
-  s.swift_versions = [4.2]
+  s.swift_versions = ['4.2', '5']
   s.requires_arc = true
   s.ios.deployment_target = '8.0'
   s.osx.deployment_target = '10.10'
@@ -42,5 +42,5 @@ Pod::Spec.new do |s|
   s.public_header_files = 'Sources/CgRPC/shim/cgrpc.h'
 
   s.dependency 'gRPC-Core', '~> 1.23.0'
-  s.dependency 'SwiftProtobuf', '~> 1.5.0'
+  s.dependency 'SwiftProtobuf', '~> 1.7.0'
 end