Update build-proto target in Makefile to use the same version used for the creation of the *.pb.go files

[gab-arrobo]

The build-proto target in Makefile needs to be accordingly updated because it is currently using an old Docker image to create the GO code from proto files. Below are the versions used to create the latest code:

// versions:
// 	protoc-gen-go v1.35.1
// 	protoc        v5.28.2
// source: pfcpsim.proto

Because of the discrepancy of the (old) version used by build-proto, newer images are not getting push to registries (DockerHub, Aether)