Fix Checkstyle suppressions DTD link.
diff --git a/checkstyle-suppressions.xml b/checkstyle-suppressions.xml
index c2dd707..fd98272 100644
--- a/checkstyle-suppressions.xml
+++ b/checkstyle-suppressions.xml
@@ -18,7 +18,7 @@
 -->
 
 <!DOCTYPE suppressions PUBLIC
-    "-//Puppy Crawl//DTD Suppressions 1.0//EN"
+    -//Checkstyle//DTD SuppressionFilter Configuration 1.0//EN
     "https://checkstyle.org/dtds/suppressions_1_0.dtd">
 
 <suppressions>