Upgrade siddhi

Author: dnwick

pom.xml

@@ -45,7 +45,7 @@
     </profiles>
 
     <properties>
-        <siddhi.version>5.1.21-SNAPSHOT</siddhi.version>
+        <siddhi.version>5.1.21</siddhi.version>
         <log4j.version>2.17.1</log4j.version>
         <testng.version>6.11</testng.version>
         <jacoco.version>0.7.9</jacoco.version>