Bump guava from 28.1-jre to 29.0-jre in /plugin/core

Bumps [guava](https://github.com/google/guava) from 28.1-jre to 29.0-jre.
- [Release notes](https://github.com/google/guava/releases)
- [Commits](https://github.com/google/guava/commits)

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

Author: dependabot[bot]

plugin/core/pom.xml

@@ -44,7 +44,7 @@
       <groupId>com.google.guava</groupId>
       <artifactId>guava</artifactId>
       <!-- version 28.1 corresponds to the grpc version 1.28.0 -->
-      <version>28.1-jre</version>
+      <version>29.0-jre</version>
     </dependency>
     <dependency>
       <groupId>org.apache.commons</groupId>