Remove newline from regex for shortcode

src/components/compose.jsx

@@ -131,7 +131,7 @@ const HASHTAG_RE = new RegExp(
 // https://github.com/mastodon/mastodon/blob/23e32a4b3031d1da8b911e0145d61b4dd47c4f96/app/models/custom_emoji.rb#L31
 const SHORTCODE_RE_FRAGMENT = '[a-zA-Z0-9_]{2,}';
 const SCAN_RE = new RegExp(
-  `([^A-Za-z0-9_:\\n]|^)(:${SHORTCODE_RE_FRAGMENT}:)(?=[^A-Za-z0-9_:]|$)`,
+  `(^|[^=\\/\\w])(:${SHORTCODE_RE_FRAGMENT}:)(?=[^A-Za-z0-9_:]|$)`,
   'g',
 );