fix: fix Concatenation test by accepting new insta snapshot

The new behavior is reasonable. In case of a double empty concatenation,
which is already pretty uncommon, the lint would suggest to remove the
second empty concat first instead of the first empty concat.

bin/tests/snapshots/main__empty_list_concat.snap

@@ -1,7 +1,6 @@
 ---
 source: bin/tests/main.rs
-expression: "&out"
-
+expression: "& out"
 ---
 [W23] Warning: Unnecessary concatenation with empty list
    ╭─[data/empty_list_concat.nix:6:4]
@@ -32,10 +31,9 @@ expression: "&out"
     ·           ╰──────── Concatenation with the empty list, [], is a no-op
 ────╯
 [W23] Warning: Unnecessary concatenation with empty list
-    ╭─[data/empty_list_concat.nix:15:4]
+    ╭─[data/empty_list_concat.nix:15:10]
     │
  15 │   ([] ++ [] ++ [])
-    ·    ────┬───  
-    ·        ╰───── Concatenation with the empty list, [], is a no-op
+    ·          ────┬───  
+    ·              ╰───── Concatenation with the empty list, [], is a no-op
 ────╯
-