Bump com.fasterxml.jackson.core:jackson-annotations from 2.20 to 2.21

Bumps [com.fasterxml.jackson.core:jackson-annotations](https://github.com/FasterXML/jackson) from 2.20 to 2.21.
- [Commits](https://github.com/FasterXML/jackson/commits)

---
updated-dependencies:
- dependency-name: com.fasterxml.jackson.core:jackson-annotations
  dependency-version: '2.21'
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Closes #249

Change-Id: Idba259f8e2f30a4a971acb5730a1716e07b76917
diff --git a/pom.xml b/pom.xml
index ccef224..528ec3e 100644
--- a/pom.xml
+++ b/pom.xml
@@ -63,7 +63,7 @@
     <jersey.version>4.0.1</jersey.version>
     <log4j.version>2.25.3</log4j.version>
     <jackson.version>2.20.1</jackson.version>
-    <jackson.mainversion>2.20</jackson.mainversion>
+    <jackson.mainversion>2.21</jackson.mainversion>
     <lucene.version>5.0.0</lucene.version>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
   </properties>