Work around type inference issue in varray![]

When passing &varray[...] to a method accepting &OutArray, rustc will fail
compilation, as the involved types don't seem to be eligible for auto-deref
coercion. The explicit `as` cast gives the compiler the necessary type hints.

Author: Bromeon

godot-core/src/builtin/collections/array.rs

@@ -1625,7 +1625,8 @@ macro_rules! varray {
                 array.push(&$elements.to_variant());
             )*
             array
-        }
+        } as $crate::builtin::VariantArray
+        // The `as` cast is necessary for Deref coercion to OutArray; type inference doesn't seem to pick it up otherwise.
     };
 }