Set group-ownership of files to 'agones' group.

Creating a non-system user named 'agones' also creates a group named
'agones'. For consistency, the files should be owned by that group.

Signed-off-by: Paul "Hampy" Hampson <p_hampson@wargaming.net>

cmd/sdk-server/Dockerfile

@@ -17,8 +17,8 @@ FROM alpine:3.11
 RUN apk --update add ca-certificates && \
     adduser -D -u 1000 agones
 
-COPY --chown=agones:root ./bin/sdk-server.linux.amd64 /home/agones/sdk-server
-COPY --chown=agones:root ./bin/LICENSES ./bin/dependencies-src.tgz /home/agones/
+COPY --chown=agones:agones ./bin/sdk-server.linux.amd64 /home/agones/sdk-server
+COPY --chown=agones:agones ./bin/LICENSES ./bin/dependencies-src.tgz /home/agones/
 
 USER 1000
 ENTRYPOINT ["/home/agones/sdk-server"]