Upgrade Google Guava library

Author: Daniel Michalski

pom.xml

@@ -21,7 +21,7 @@
 		<postgresql.version>42.2.14</postgresql.version>
 		<liquibase.version>4.0.0</liquibase.version>
 		<lombok.version>1.18.12</lombok.version>
-		<guava.version>29.0-jre</guava.version>
+		<guava.version>30.1.1-jre</guava.version>
 		<jcalendar.version>1.4</jcalendar.version>
 		<maven.compiler.plugin.version>3.8.1</maven.compiler.plugin.version>
 		<checkstyle.plugin.version>3.1.0</checkstyle.plugin.version>