KNOX-2221 - Upgrade shiro to 1.5.3 (#360)

Signed-off-by: Kevin Risden <krisden@apache.org>
diff --git a/pom.xml b/pom.xml
index 0fb005a..7e7225f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -242,7 +242,7 @@
         <pac4j.version>3.8.3</pac4j.version>
         <protobuf.version>3.11.4</protobuf.version>
         <rest-assured.version>4.3.0</rest-assured.version>
-        <shiro.version>1.4.2</shiro.version>
+        <shiro.version>1.5.3</shiro.version>
         <shrinkwrap.version>1.2.6</shrinkwrap.version>
         <shrinkwrap.descriptors.version>2.0.0</shrinkwrap.descriptors.version>
         <slf4j.version>1.7.30</slf4j.version>