deps: update dependency com.google.guava:guava-bom to v28.2-android (#68)

Author: renovate-bot

pom.xml

@@ -158,7 +158,7 @@
  <grpc.version>1.27.0</grpc.version>
  <protobuf.version>3.11.1</protobuf.version>
  <junit.version>4.13</junit.version>
- <guava.version>28.1-android</guava.version>
+ <guava.version>28.2-android</guava.version>
  <threeten.version>1.4.1</threeten.version>
  <javax.annotations.version>1.3.2</javax.annotations.version>
  <animal-sniffer.version>1.18</animal-sniffer.version>