Fix test failure

Author: botahamec

clippy_lints/src/unnecessary_box_returns.rs

@@ -81,7 +81,7 @@ impl UnnecessaryBoxReturns {
                         // be changed, so this can't be MachineApplicable
                         Applicability::Unspecified,
                     );
-                    diagnostic.help("Changing this also requires a change to the return expressions in this function");
+                    diagnostic.help("changing this also requires a change to the return expressions in this function");
                 },
             );
         }

tests/ui/unnecessary_box_returns.stderr

@@ -4,7 +4,7 @@ error: boxed return of the sized type `usize`
 LL |     fn baz(&self) -> Box<usize>;
    |                      ^^^^^^^^^^ help: try: `usize`
    |
-   = help: Changing this also requires a change to the return expressions in this function
+   = help: changing this also requires a change to the return expressions in this function
    = note: `-D clippy::unnecessary-box-returns` implied by `-D warnings`
 
 error: boxed return of the sized type `usize`
@@ -13,23 +13,23 @@ error: boxed return of the sized type `usize`
 LL |     fn baz(&self) -> Box<usize> {
    |                      ^^^^^^^^^^ help: try: `usize`
    |
-   = help: Changing this also requires a change to the return expressions in this function
+   = help: changing this also requires a change to the return expressions in this function
 
 error: boxed return of the sized type `usize`
   --> $DIR/unnecessary_box_returns.rs:24:21
    |
 LL | fn boxed_usize() -> Box<usize> {
    |                     ^^^^^^^^^^ help: try: `usize`
    |
-   = help: Changing this also requires a change to the return expressions in this function
+   = help: changing this also requires a change to the return expressions in this function
 
 error: boxed return of the sized type `Foo`
   --> $DIR/unnecessary_box_returns.rs:29:20
    |
 LL | fn _boxed_foo() -> Box<Foo> {
    |                    ^^^^^^^^ help: try: `Foo`
    |
-   = help: Changing this also requires a change to the return expressions in this function
+   = help: changing this also requires a change to the return expressions in this function
 
 error: aborting due to 4 previous errors