refactor(natu): remove single-use binding rule

src/natu/testdata/clean.nix

@@ -2,18 +2,18 @@
 
 let
   first = 1;
-  second = first; # NOLINT(single_use_binding)
+  second = first;
 in {
   firstField = first;
   secondField = second;
   nested = let
-    innerSecond = innerFirst; # NOLINT(single_use_binding)
-    innerFirst = first; # NOLINT(single_use_binding)
+    innerSecond = innerFirst;
+    innerFirst = first;
   in {
     result = innerSecond;
   };
   parameter = first: let
-    usesParameter = first; # NOLINT(single_use_binding)
+    usesParameter = first;
   in {
     result = usesParameter;
   };

src/natu/testdata/lint_findings.nix

@@ -1,9 +1,9 @@
 let
-  second = first; # NOLINT(single_use_binding)
+  second = first;
   first = 1;
-  nested = let # NOLINT(single_use_binding)
-    nestedFirst = first; # NOLINT(single_use_binding)
-    nestedSecond = nestedFirst; # NOLINT(single_use_binding)
+  nested = let
+    nestedFirst = first;
+    nestedSecond = nestedFirst;
   in {
     result = nestedSecond;
   };