refactor!: Remove underscore (#10648)

BREAKING CHANGE: Removed the `underscore()` formatter. Use `underline()` instead.

packages/formatters/src/formatters.ts

@@ -56,17 +56,6 @@ export function bold<Content extends string>(content: Content): `**${Content}**`
 	return `**${content}**`;
 }
 
-/**
- * Formats the content into underscored text.
- *
- * @typeParam Content - This is inferred by the supplied content
- * @param content - The content to wrap
- * @deprecated Use {@link underline} instead.
- */
-export function underscore<Content extends string>(content: Content): `__${Content}__` {
-	return underline(content);
-}
-
 /**
  * Formats the content into underlined text.
  *