Update Examples to use .singleton (#742)

Author: chieffancypants

Examples/GetHTML/GetHTML.swift

@@ -18,7 +18,7 @@ import NIOCore
 @main
 struct GetHTML {
     static func main() async throws {
-        let httpClient = HTTPClient(eventLoopGroupProvider: .createNew)
+        let httpClient = HTTPClient(eventLoopGroupProvider: .singleton)
         do {
             let request = HTTPClientRequest(url: "https://apple.com")
             let response = try await httpClient.execute(request, timeout: .seconds(30))

Examples/GetJSON/GetJSON.swift

@@ -33,7 +33,7 @@ struct Comic: Codable {
 @main
 struct GetJSON {
     static func main() async throws {
-        let httpClient = HTTPClient(eventLoopGroupProvider: .createNew)
+        let httpClient = HTTPClient(eventLoopGroupProvider: .singleton)
         do {
             let request = HTTPClientRequest(url: "https://xkcd.com/info.0.json")
             let response = try await httpClient.execute(request, timeout: .seconds(30))

Examples/StreamingByteCounter/StreamingByteCounter.swift

@@ -18,7 +18,7 @@ import NIOCore
 @main
 struct StreamingByteCounter {
     static func main() async throws {
-        let httpClient = HTTPClient(eventLoopGroupProvider: .createNew)
+        let httpClient = HTTPClient(eventLoopGroupProvider: .singleton)
         do {
             let request = HTTPClientRequest(url: "https://apple.com")
             let response = try await httpClient.execute(request, timeout: .seconds(30))