wip: rewrite package.swift to use local plugin package

Author: euanh

.github/workflows/pull_request.yml

@@ -32,6 +32,7 @@ jobs:
             - name: Build the example
               run: |
                   cd Examples/HelloWorldHummingbird
+                  sed -i'.bak' -e '/swift-container-plugin/ s/(url:.*),/(path: "..\/.."),/' Package.swift
                   swift package \
                       --swift-sdk x86_64-swift-linux-musl \
                       --allow-network-connections all \

Examples/HelloWorldHummingbird/Package.swift

@@ -26,5 +26,4 @@ let package = Package(
     targets: [
         .executableTarget(name: "hello-world", dependencies: [.product(name: "Hummingbird", package: "hummingbird")])
     ]
-
 )