test-driver: rm spurious blank line.

* lib/test-driver (print_usage): remove spurious blank line.
Report from Bruno,
https://lists.gnu.org/archive/html/automake/2024-06/msg00075.html
diff --git a/lib/test-driver b/lib/test-driver
index 5c3ae82..dc38f62 100755
--- a/lib/test-driver
+++ b/lib/test-driver
@@ -51,7 +51,6 @@
 The '--test-name', '--log-file' and '--trs-file' options are mandatory.
 See the GNU Automake documentation for information.
 
-
 Report bugs to <bug-automake@gnu.org>.
 GNU Automake home page: <https://www.gnu.org/software/automake/>.
 General help using GNU software: <https://www.gnu.org/gethelp/>.