style: collapse partition_treats_unknown_extensions_as_objects inputs

rustfmt wants the two-element vec! on one line. Matches the style of
the other partition tests in the same module (single-line vec! when
the elements fit).

Addresses CodeRabbit review feedback on #306.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: zackees

crates/fbuild-build/src/avr/avr_linker.rs

@@ -264,10 +264,7 @@ mod tests {
         // Defensive: anything that isn't .a (e.g. .lo, .obj, no extension)
         // is treated as an object and archived. This is safer than letting
         // an unknown extension fall through to a raw avr-gcc positional arg.
-        let inputs = vec![
-            PathBuf::from("/tmp/weird.lo"),
-            PathBuf::from("/tmp/no_ext"),
-        ];
+        let inputs = vec![PathBuf::from("/tmp/weird.lo"), PathBuf::from("/tmp/no_ext")];
         let (archives, objects) = partition_link_inputs(&inputs);
         assert!(archives.is_empty());
         assert_eq!(objects.len(), 2);