Adding suggested exception from @PauloMigAlmeida

When the OTP code is requested, then the special GHOTPRequiredException
is raised instead of the generic IOException. This differentiates
between an OTP request and a failed password.

src/test/java/org/kohsuke/github/Github2faTest.java

@@ -33,7 +33,7 @@ public class Github2faTest  extends AbstractGitHubWireMockTest {
 		GHAuthorization token=null;
 		try {
 			token = gitHub.createToken(asList, nameOfToken, "this is a test token created by a unit test");
-		}catch (IOException ex) {
+		}catch (GHOTPRequiredException ex) {
 			//ex.printStackTrace();
 			// under 2fa mode this exception is expected, and is necessary
 			// as the exception is called, GitHub will generate and send an OTP to the users SMS