[#68] Makefile: Drop GO111MODULE usages

It is ignored since go1.17.

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

Makefile

@@ -9,15 +9,12 @@ VERSION ?= $(shell git describe --tags --match "v*" --abbrev=8 --dirty --always)
 dep:
 	@printf "⇒ Tidy requirements : "
 	CGO_ENABLED=0 \
-	GO111MODULE=on \
 	go mod tidy -v && echo OK
 	@printf "⇒ Download requirements: "
 	CGO_ENABLED=0 \
-	GO111MODULE=on \
 	go mod download && echo OK
 	@printf "⇒ Install test requirements: "
 	CGO_ENABLED=0 \
-	GO111MODULE=on \
 	go test ./... && echo OK
 
 # Run all code formatters
@@ -27,14 +24,14 @@ fmts: fmt imports
 fmt:
 	@echo "⇒ Processing gofmt check"
 	@for f in `find . -type f -name '*.go' -not -path './vendor/*' -not -name '*.pb.go' -prune`; do \
-		GO111MODULE=on gofmt -s -w $$f; \
+		gofmt -s -w $$f; \
 	done
 
 # Reformat imports
 imports:
 	@echo "⇒ Processing goimports check"
 	@for f in `find . -type f -name '*.go' -not -path './vendor/*' -not -name '*.pb.go' -prune`; do \
-		GO111MODULE=on goimports -w $$f; \
+		goimports -w $$f; \
 	done
 
 # Regenerate code for proto files
@@ -56,7 +53,7 @@ protoc:
 # Run Unit Test with go test
 test:
 	@echo "⇒ Running go test"
-	@GO111MODULE=on go test ./... -count=1
+	@go test ./... -count=1
 
 # Run linters
 lint: