Bump protobuf-java from 2.6.1 to 3.15.6 in /java#34

dependabot[bot] wants to merge 1 commit intomastermoazreyad/singa:masterfrom

2d51dependabot/maven/java/com.google.protobuf-protobuf-java-3.15.6moazreyad/singa:2d51dependabot/maven/java/com.google.protobuf-protobuf-java-3.15.6Copy head branch name to clipboard