testcurl/https: do not enforce TLSv1

Usage of concrete TLS version is not future-proof. Relay on default
version setting by libcurl/TLS lib.

src/testcurl/https/test_https_get_iovec.c

@@ -408,7 +408,7 @@ main (int argc, char *const *argv)
   }
 
   errorCount +=
-    test_secure_get (NULL, NULL, CURL_SSLVERSION_TLSv1);
+    test_secure_get (NULL, NULL, CURL_SSLVERSION_DEFAULT);
   errorCount += testEmptyGet (0);
   curl_global_cleanup ();