SEBA-902 single-olt tests;
Pin protoc-gen-go to 1.3.2 to resolve compatibility issue;
Run go mod tidy / go mod vendor on importer;
Add Go Module support to demotest

Change-Id: Ifde824fc9a6317b0adc1e12bea54ee1f9b788906
diff --git a/Dockerfile b/Dockerfile
index f1c10e6..0f92fe3 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -27,10 +27,7 @@
 	gcc=4:8.3.0-1 \
 	curl=7.64.0-4 \
 	unzip=6.0-23+deb10u1
-RUN go get -u "google.golang.org/grpc" \
-    && go get "github.com/golang/protobuf/proto" \
-    && go get -v "github.com/grpc-ecosystem/grpc-gateway/protoc-gen-grpc-gateway" \
-    && go get -v "github.com/golang/protobuf/protoc-gen-go@v1.3.2"
+RUN go get -v "github.com/golang/protobuf/protoc-gen-go@v1.3.2"
 RUN mkdir /app
 COPY . /app/
 WORKDIR /app
@@ -50,4 +47,3 @@
 COPY --from=build-env /app/main .
 COPY --from=build-env /app/proto/importer.pb.go .
 ENTRYPOINT ["./main"]
-