Update upstream grpc-swift to v1.7.3

Author: vyshane

Package.resolved

@@ -16,7 +16,7 @@ let package = Package(
             targets: ["CombineGRPC"]),
     ],
     dependencies: [
-        .package(url: "https://github.com/grpc/grpc-swift.git", .exact("1.7.2")),
+        .package(url: "https://github.com/grpc/grpc-swift.git", .exact("1.7.3")),
         .package(url: "https://github.com/CombineCommunity/CombineExt.git", from: "1.5.1"),
     ],
     targets: [

Package.swift

@@ -174,7 +174,7 @@ 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](https://github.com/grpc/grpc-swift/releases/download/1.7.2/protoc-grpc-swift-plugins-1.7.2.zip). Unarchive the downloaded file and move the binaries from the `bin/` directory to somewhere in your `$PATH`.
+Next, download the [swift and grpc-swift protoc plugins](https://github.com/grpc/grpc-swift/releases/download/1.7.3/protoc-grpc-swift-plugins-1.7.3.zip). Unarchive the downloaded file and move the binaries from the `bin/` directory to somewhere in your `$PATH`.
 
 Now you are ready to generate Swift code from protobuf interface definition files.