fix: pom.xml to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-COMFASTERXMLJACKSONCORE-15365924

Author: snyk-bot

pom.xml

@@ -181,7 +181,7 @@
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
-            <version>2.21.0</version>
+            <version>2.21.1</version>
         </dependency>
         <dependency>
             <groupId>com.slack.api</groupId>