Replace unicode character, fixes twbs#25391

Author: rvanlaak

scss/mixins/_hover.scss

@@ -3,7 +3,7 @@
 // Hover mixin and `$enable-hover-media-query` are deprecated.
 //
 // Origally added during our alphas and maintained during betas, this mixin was
-// designed to prevent `:hover` stickiness on iOS—an issue where hover styles
+// designed to prevent `:hover` stickiness on iOS-an issue where hover styles
 // would persist after initial touch.
 //
 // For backward compatibility, we've kept these mixins and updated them to