Update upstream grpc-swift to v1.0.0-alpha.20

Author: vyshane

CombineGRPC.podspec

@@ -18,7 +18,7 @@ Pod::Spec.new do |spec|
   spec.tvos.deployment_target = "13.0"
   spec.source_files = 'Sources/CombineGRPC/**/*.swift'
 
-  spec.dependency "gRPC-Swift", "1.0.0-alpha.19"
+  spec.dependency "gRPC-Swift", "1.0.0-alpha.20"
   spec.dependency "CombineExt", "1.2.0"
 
 end

Package.resolved

@@ -15,8 +15,8 @@
         "repositoryURL": "https://github.com/grpc/grpc-swift.git",
         "state": {
           "branch": null,
-          "revision": "640b0ef1d0be63bda0ada86786cfda678ab2aae9",
-          "version": "1.0.0-alpha.19"
+          "revision": "e2e138df61dcbfc2dc1cf284fdab6f983539ab48",
+          "version": "1.0.0-alpha.20"
         }
       },
       {

Package.swift

@@ -16,7 +16,7 @@ let package = Package(
             targets: ["CombineGRPC"]),
     ],
     dependencies: [
-        .package(url: "https://github.com/grpc/grpc-swift.git", .exact("1.0.0-alpha.19")),
+        .package(url: "https://github.com/grpc/grpc-swift.git", .exact("1.0.0-alpha.20")),
         .package(url: "https://github.com/CombineCommunity/CombineExt.git", from: "1.2.0"),
     ],
     targets: [

README.md

@@ -168,8 +168,8 @@ To generate Swift code from your .proto files, you'll need to first install the
 brew install protobuf
 ```
 
-Next, download the swift and grpc-swift protoc plugins from the the latest version of grpc-swift. Currently that means [protoc-grpc-swift-plugins-1.0.0-alpha.19.zip
-](https://github.com/grpc/grpc-swift/releases/download/1.0.0-alpha.19/protoc-grpc-swift-plugins-1.0.0-alpha.19.zip). Unarchive the downloaded file and move the binaries from the `bin/` directory somewhere in your `$PATH`.
+Next, download the swift and grpc-swift protoc plugins from the the latest version of grpc-swift. Currently that means [protoc-grpc-swift-plugins-1.0.0-alpha.20.zip
+](https://github.com/grpc/grpc-swift/releases/download/1.0.0-alpha.20/protoc-grpc-swift-plugins-1.0.0-alpha.20.zip). Unarchive the downloaded file and move the binaries from the `bin/` directory somewhere in your `$PATH`.
 
 Now you are ready to generate Swift code from protobuf interface definition files.