build: update gnulib to fix a syntax error in a test

diff --git a/gnulib b/gnulib
index 7b3b57be85df017c3ac1cf362dc645a701d8b80b..db37bb3e918ce69fd0bf5e45752edd07f49ae07d 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 7b3b57be85df017c3ac1cf362dc645a701d8b80b
+Subproject commit db37bb3e918ce69fd0bf5e45752edd07f49ae07d