Fix Checkstyle XML.
diff --git a/core/checkstyle-suppressions.xml b/core/checkstyle-suppressions.xml
index d385aaf..1464f47 100644
--- a/core/checkstyle-suppressions.xml
+++ b/core/checkstyle-suppressions.xml
@@ -1,6 +1,6 @@
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE suppressions PUBLIC
- -//Checkstyle//DTD SuppressionFilter Configuration 1.0//EN
+ "-//Checkstyle//DTD SuppressionFilter Configuration 1.0//EN"
"https://checkstyle.org/dtds/suppressions_1_0.dtd">
<!--
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