BUG/MINOR: ssl: Fix potential leak in cli_parse_update_ocsp_response

In some extremely unlikely case (or even impossible for now), we might
exit cli_parse_update_ocsp_response without raising an error but with a
filled 'err' buffer. It was not properly free'd.

It does not need to be backported.
diff --git a/src/ssl_ocsp.c b/src/ssl_ocsp.c
index 979a87b..8a7cb27 100644
--- a/src/ssl_ocsp.c
+++ b/src/ssl_ocsp.c
@@ -1397,6 +1397,8 @@
 
 	task_wakeup(ocsp_update_task, TASK_WOKEN_MSG);
 
+	free(err);
+
 	return 0;
 
 end: