fix typo

clippy_lints/src/drop_forget_ref.rs

@@ -180,7 +180,7 @@ const DROP_COPY_SUMMARY: &str = "calls to `std::mem::drop` with a value that imp
 const FORGET_COPY_SUMMARY: &str = "calls to `std::mem::forget` with a value that implements `Copy`. \
                                    Forgetting a copy leaves the original intact";
 const DROP_NON_DROP_SUMMARY: &str = "call to `std::mem::drop` with a value that does not implement `Drop`. \
-                                 Dropping such a type only extends it's contained lifetimes";
+                                 Dropping such a type only extends its contained lifetimes";
 const FORGET_NON_DROP_SUMMARY: &str = "call to `std::mem::forget` with a value that does not implement `Drop`. \
                                    Forgetting such a type is the same as dropping it";
 

tests/ui/drop_non_drop.stderr

@@ -1,4 +1,4 @@
-error: call to `std::mem::drop` with a value that does not implement `Drop`. Dropping such a type only extends it's contained lifetimes
+error: call to `std::mem::drop` with a value that does not implement `Drop`. Dropping such a type only extends its contained lifetimes
   --> $DIR/drop_non_drop.rs:22:5
    |
 LL |     drop(Foo);
@@ -11,7 +11,7 @@ note: argument has type `main::Foo`
 LL |     drop(Foo);
    |          ^^^
 
-error: call to `std::mem::drop` with a value that does not implement `Drop`. Dropping such a type only extends it's contained lifetimes
+error: call to `std::mem::drop` with a value that does not implement `Drop`. Dropping such a type only extends its contained lifetimes
   --> $DIR/drop_non_drop.rs:37:5
    |
 LL |     drop(Baz(Foo));