Updating SLF4J

git-svn-id: https://svn.apache.org/repos/asf/santuario/xml-security-java/trunk@1865096 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/pom.xml b/pom.xml
index 5b367bf..a153163 100644
--- a/pom.xml
+++ b/pom.xml
@@ -543,7 +543,7 @@
 
     <properties>
         <xml.apis.version>1.4.01</xml.apis.version>
-        <slf4j.version>1.7.26</slf4j.version>
+        <slf4j.version>1.7.28</slf4j.version>
         <xalan.version>2.7.2</xalan.version>
         <xerces.version>2.12.0</xerces.version>
         <junit.version>5.5.0</junit.version>