update to use php-http/httplug:^2.0

[one-horned-flying]

when will there be a release to require:

"php-http/httplug": "^2.0",

??

currently the composer.json requires

"php-http/httplug": "^1.0",

[one-horned-flying]

This is all that is needed. The composer tests pass as well

$ git diff origin/master
diff --git a/composer.json b/composer.json
index 2dadf57..b74ec1a 100644
--- a/composer.json
+++ b/composer.json
@@ -12,7 +12,7 @@
     ],
     "require": {
         "php": "^7.1",
-        "php-http/httplug": "^1.0",
+        "php-http/httplug": "^2.0",
         "react/http-client": "~0.5.9",
         "react/dns": "^1.0|^0.4.15",
         "react/socket": "^1.0",
@@ -21,7 +21,7 @@
         "php-http/discovery": "^1.0"
     },
     "require-dev": {
-        "php-http/client-integration-tests": "^0.6",
+        "php-http/client-integration-tests": "^2.0",
         "php-http/message": "^1.0",
         "phpunit/phpunit": "^4.8.36 || ^5.4"
     },
diff --git a/src/Client.php b/src/Client.php
index 21d3389..946807d 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -79,7 +79,7 @@ class Client implements HttpClient, HttpAsyncClient
     /**
      * {@inheritdoc}
      */
-    public function sendRequest(RequestInterface $request)
+    public function sendRequest(RequestInterface $request): ResponseInterface
     {
         $promise = $this->sendAsyncRequest($request);

[shulard]

Hello @jraubswitch !

I've just created the PR based on your suggested changes.