Fixes SocketException: Resource temporarily unavailable (connect failed)

[damianszczepanik]

Fixes SocketException that is thrown after 100+ requests.

Problem
URL connection was not disposed like the IO streams so APIClient claims exception when trying to establish new connection that is result of 100+ opened connection that should be closed or reused.

Stacktrace:

Exception in thread "main" java.net.SocketException: Resource temporarily unavailable (connect failed)
        at java.base/java.net.PlainSocketImpl.socketConnect(Native Method)
        at java.base/java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:412)
        at java.base/java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:255)
        at java.base/java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:237)
        at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
        at java.base/java.net.Socket.connect(Socket.java:609)
        at java.base/sun.security.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:305)
        at java.base/sun.security.ssl.BaseSSLSocketImpl.connect(BaseSSLSocketImpl.java:173)
        at java.base/sun.net.NetworkClient.doConnect(NetworkClient.java:182)
        at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:509)
        at java.base/sun.net.www.http.HttpClient.openServer(HttpClient.java:604)
        at java.base/sun.net.www.protocol.https.HttpsClient.<init>(HttpsClient.java:266)
        at java.base/sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:373)
        at java.base/sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:207)
        at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1187)
        at java.base/sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1081)
        at java.base/sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:193)
        at java.base/sun.net.www.protocol.http.HttpURLConnection.getOutputStream0(HttpURLConnection.java:1367)
        at java.base/sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:1342)
        at java.base/sun.net.www.protocol.https.HttpsURLConnectionImpl.getOutputStream(HttpsURLConnectionImpl.java:246)
        at com.gurock.testrail.APIClient.sendRequest(APIClient.java:162)
        at com.gurock.testrail.APIClient.sendPost(APIClient.java:132)

Solution:
URL connection is closed so number of opened connection does not increase after each request

[damianszczepanik]

@jonridera can you review/merge this pull request?