EA-1511: Implement Heartbeats

Author: sleipi

.gitignore

@@ -4,3 +4,4 @@
 var/
 build
 .php_cs.cache
+tests/.phpunit.result.cache

README.md

@@ -12,9 +12,12 @@ https://docs.opsgenie.com/docs/alert-api
 * Create Alert
 * Get specific Alert (by alias) from API
 * Close Alert 
+* Ping Heatbeat
 
 ## How-To-Use
 
+Create / Get / Close Alert 
+
 ````php
 # named constructor to create a client (for EU)
 $client = AlertApiClient::createForEUApi(getenv(UPSGENIE_TOKEN));
@@ -31,3 +34,17 @@ if($response->isSuccessful()){
     $client->closeAlert(new CloseAlertRequest($alert->getAlias()));
 }
 ````
+
+
+Ping Heartbeat
+
+````php
+$token = "xxx-xxx-xxx";
+$client = new HeartbeatApiClient(HttpClient::createForEUApi(getenv(UPSGENIE_TOKEN)));
+do {
+    $result = $client->sendPing(new PingRequest('beat'));
+    var_dump($result, $result->isSuccessful());
+    sleep(60);
+} while(true);
+
+````

composer.json

@@ -13,7 +13,7 @@
         "guzzlehttp/guzzle": "^6.3"
     },
     "require-dev": {
-        "phpunit/phpunit": "^7.0",
+        "phpunit/phpunit": "^8.0",
         "friendsofphp/php-cs-fixer": "^2.12",
         "phpstan/phpstan": "^0.10.5"
     },