Fix swift-nio benchmarks (#6428)

frameworks/Swift/swift-nio/app/Sources/main.swift

@@ -41,9 +41,9 @@ private final class HTTPHandler: ChannelInboundHandler {
         switch self.unwrapInboundIn(data) {
         case .head(let request):
             switch request.uri {
-            case "/p":
+            case "/plaintext":
                 self.processPlaintext(context: context)
-            case "/j":
+            case "/json":
                 do {
                     try self.processJSON(context: context)
                 } catch {

frameworks/Swift/swift-nio/benchmark_config.json

@@ -2,8 +2,8 @@
   "framework": "swift-nio",
   "tests": [{
     "default": {
-      "json_url": "/j",
-      "plaintext_url": "/p",
+      "json_url": "/json",
+      "plaintext_url": "/plaintext",
       "port": 8080,
       "approach": "Realistic",
       "classification": "Platform",

frameworks/Swift/swift-nio/swift-nio.dockerfile

@@ -1,7 +1,7 @@
 # ================================
 # Build image
 # ================================
-FROM swift:5.1 as build
+FROM swift:5.3 as build
 WORKDIR /build
 
 # Copy entire repo into container
@@ -15,7 +15,7 @@ RUN swift build \
 # ================================
 # Run image
 # ================================
-FROM ubuntu:18.04
+FROM swift:5.3-slim
 WORKDIR /run
 
 # Install Swift dependencies