Update actions/checkout from v2.3.2 to v2.3.3 #156.

Author: Gary Gregory

src/changes/changes.xml

@@ -66,6 +66,9 @@ The <action> type attribute can be add,update,fix,remove.
       <action dev="ggregory" type="update" due-to="Dependabot">
         Update spotbugs from 4.1.2 to 4.1.3 #158.
       </action>
+      <action dev="ggregory" type="update" due-to="Dependabot">
+        Update actions/checkout from v2.3.2 to v2.3.3 #156.
+      </action>
     </release>
     <!-- The release date is the date RC is cut -->
     <release version="2.8.0" date="2020-09-05" description="Java 8 required.">