lib/utilities: quote SC2295

Doesn't show up on my shellcheck 0.7.2, but does for NoahGorny!

lib/utilities.bash

@@ -11,7 +11,7 @@ function _bash-it-get-component-name-from-path() {
 	# filename without path
 	filename="${1##*/}"
 	# filename without path or priority
-	filename="${filename##*${BASH_IT_LOAD_PRIORITY_SEPARATOR?}}"
+	filename="${filename##*"${BASH_IT_LOAD_PRIORITY_SEPARATOR?}"}"
 	# filename without path, priority or extension
 	echo "${filename%.*.bash}"
 }