Bump guava from 29.0-jre to 21.1-jre

Change-Id: I9c0723115070cd3319e666e4df6c4fbe1745490b
Reviewed-on: https://korap.ids-mannheim.de/gerrit/c/KorAP/Koral/+/6278
Reviewed-by: Marc Kupietz <kupietz@ids-mannheim.de>
diff --git a/pom.xml b/pom.xml
index d26ab7f..134bcdd 100644
--- a/pom.xml
+++ b/pom.xml
@@ -80,7 +80,7 @@
 		<dependency>
 			<groupId>com.google.guava</groupId>
 			<artifactId>guava</artifactId>
-			<version>[29.0-jre,)</version>
+			<version>31.1-jre</version>
 		</dependency>
 		<dependency>
 			<groupId>com.fasterxml.jackson.core</groupId>