Update Cocoapods for 1.4.2 (#1281)

CGRPCZlib.podspec

@@ -2,7 +2,7 @@ Pod::Spec.new do |s|
 
     s.name = 'CGRPCZlib'
     s.module_name = 'CGRPCZlib'
-    s.version = '1.4.1'
+    s.version = '1.4.2'
     s.license = { :type => 'Apache 2.0', :file => 'LICENSE' }
     s.summary = 'Compression library that provides in-memory compression and decompression functions'
     s.homepage = 'https://www.grpc.io'

gRPC-Swift-Plugins.podspec

@@ -1,7 +1,7 @@
 Pod::Spec.new do |s|
 
     s.name = 'gRPC-Swift-Plugins'
-    s.version = '1.4.1'
+    s.version = '1.4.2'
     s.license = { :type => 'Apache 2.0', :file => 'LICENSE' }
     s.summary = 'Swift gRPC code generator plugin binaries'
     s.homepage = 'https://www.grpc.io'

gRPC-Swift.podspec

@@ -2,7 +2,7 @@ Pod::Spec.new do |s|
 
     s.name = 'gRPC-Swift'
     s.module_name = 'GRPC'
-    s.version = '1.4.1'
+    s.version = '1.4.2'
     s.license = { :type => 'Apache 2.0', :file => 'LICENSE' }
     s.summary = 'Swift gRPC code generator plugin and runtime library'
     s.homepage = 'https://www.grpc.io'