chore: bump api version to 21 [skip ci]

Author: github-actions[bot]

server/pom.xml

@@ -11,7 +11,7 @@
 
   <groupId>br.com.tasknoteapp</groupId>
   <artifactId>server</artifactId>
-  <version>20</version>
+  <version>21</version>
   <name>tasknote-api</name>
   <description>Java backend REST API to serve TaskNote frontend client</description>