Deleting Protobuf generated files

[stdevMac]

Describe the bug
When you run make clean we delete this files:

• internal/db/transaction/transaction.pb.go
• internal/db/state/state.pb.go
• internal/db/abi/abi.pb.go

Those files are generated using protoc compiler, but they should not suffer too many changes over the time, so, there is no need to add the compiler to the project dependecies