luci-mod-system: fix JSMIN Error

jsmin cannot handle regular expressions in this format, so use RegExp() instead.

fixes: #8020

Signed-off-by: Andy Chiang <AndyChiang_git@outlook.com>

modules/luci-mod-system/htdocs/luci-static/resources/view/system/repokeys.js

@@ -117,7 +117,7 @@ function removeKey(ev) {
 }
 
 function isPemFormat(content) {
-	return /-BEGIN ([A-Z ]+)?PUBLIC KEY-/.test(content);
+	return new RegExp('-BEGIN ([A-Z ]+)?PUBLIC KEY-').test(content);
 }
 
 function keyEnvironmentCheck(key) {