Update checkstyle-suppressions.xml

Fix XML.
diff --git a/src/conf/checkstyle-suppressions.xml b/src/conf/checkstyle-suppressions.xml
index d2eedd3..e4e4b3f 100644
--- a/src/conf/checkstyle-suppressions.xml
+++ b/src/conf/checkstyle-suppressions.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0"?>
-<!DOCTYPE suppressions PUBLIC -//Checkstyle//DTD SuppressionFilter Configuration 1.0//EN "https://checkstyle.org/dtds/suppressions_1_0.dtd">
+<!DOCTYPE suppressions PUBLIC "-//Checkstyle//DTD SuppressionFilter Configuration 1.0//EN" "https://checkstyle.org/dtds/suppressions_1_0.dtd">
 <!--
    Licensed to the Apache Software Foundation (ASF) under one or more
    contributor license agreements.  See the NOTICE file distributed with