bug: Fix makefile according to latest go versions

Makefile

@@ -20,14 +20,9 @@ build: vendor  ## build executable
 	@mkdir -p "$(BUILD_DIR)"
 	# go build -i ./...
 	# GOBIN="$(BUILD_DIR)" go install ./...
-	for binary in "./cmd"/* ; do \
+	for binary in $$(cd cmd ; ls) ; do \
 		name="$$(basename "$$binary")" ; \
-		go build -i "$$binary" || exit 1 ; \
-		if [ -f "$$name.exe" ]; then \
-			mv "$$name.exe" "$(BUILD_DIR)/$$name.exe" || exit 1 ; \
-		else \
-			mv "$$name" "$(BUILD_DIR)/$$name" || exit 1 ; \
-		fi ; \
+		go build -o "_build/$$binary" ./cmd/$$binary/... || exit 1 ; \
 	done