Update clippy_lints/src/no_effect.rs

Co-authored-by: Takayuki Nakata <f.seasons017@gmail.com>

clippy_lints/src/no_effect.rs

@@ -98,7 +98,7 @@ fn check_no_effect(cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'_>) -> bool {
                     NO_EFFECT_UNDERSCORE_BINDING,
                     init.hir_id,
                     stmt.span,
-                    "binding to _ prefixed variable with no side-effect"
+                    "binding to `_` prefixed variable with no side-effect"
                 );
                 return true;
             }