refactor: restrict allowed values to primitives

Signed-off-by: Athan <[email protected]>

Author: kgryte

lib/node_modules/@stdlib/_tools/remark/plugins/remark-lint-expected-html-sections/lib/validate.js

@@ -24,7 +24,7 @@ var objectKeys = require( '@stdlib/utils/keys' );
 var isObject = require( '@stdlib/assert/is-plain-object' );
 var hasOwnProp = require( '@stdlib/assert/has-own-property' );
 var isArray = require( '@stdlib/assert/is-array' );
-var isString = require( '@stdlib/assert/is-string' );
+var isString = require( '@stdlib/assert/is-string' ).isPrimitive;
 var format = require( '@stdlib/string/format' );