Add missing @Override annotation

Found via error-prone.

src/test/java/org/gaul/s3proxy/S3AwsSdkTest.java

@@ -312,6 +312,7 @@ public final class S3AwsSdkTest {
 
             // Create all-trusting host name verifier
             HostnameVerifier allHostsValid = new HostnameVerifier() {
+                @Override
                 public boolean verify(String hostname, SSLSession session) {
                     return true;
                 }