Disable clippy warning in definitions.rs

The derive_builder macro introduces some warning about Default trait
usage in version 0.10.0.

I can not reprodiuce this outside my codebase and thus feel not
comfortable to file a bug report... but the thing seems to work fine,
so just allow the relevant warning in that file:-/

gng_shared/src/definitions.rs

@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 // Copyright (C) 2020 Tobias Hunger <tobias.hunger@gmail.com>
 
+#![allow(clippy::default_trait_access)] // To work around a warning in code generated by derive_builder!
+
 //! Package configuration
 
 use itertools::Itertools;