fix: pom.xml to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JAVA-COMGOOGLEGUAVA-32236

Author: snyk-test

pom.xml

@@ -61,7 +61,7 @@
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>
-            <version>24.1.1-jre</version>
+            <version>26.0-jre</version>
         </dependency>
         <dependency>
             <groupId>junit</groupId>