Add linting with golangci-lint

To give a bit more consistency across the project with the Go
ecosystem, as well as picking up on some common errors that new
contributions can bring, enable golangci-lint, with default
configuration.

.github/workflows/lint.yml

@@ -0,0 +1,20 @@
+name: Lint project
+on: [push, pull_request]
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out source code
+        uses: actions/checkout@v3
+
+      - name: Set up Go
+        uses: actions/setup-go@v3
+        with:
+          go-version-file: 'go.mod'
+
+      - name: golangci-lint
+        uses: golangci/golangci-lint-action@v3
+        with:
+          # Make sure this matches the version we've got in our `Makefile`
+          version: v1.50.1

Makefile

@@ -1,3 +1,6 @@
+GOBASE=$(shell pwd)
+GOBIN=$(GOBASE)/bin
+
 help:
 	@echo "This is a helper makefile for oapi-codegen"
 	@echo "Targets:"
@@ -6,6 +9,15 @@ help:
 	@echo "    gin_example  generate gin example server code"
 	@echo "    tidy         tidy go mod"
 
+$(GOBIN)/golangci-lint:
+	curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(GOBIN) v1.50.1
+
+.PHONY: tools
+tools: $(GOBIN)/golangci-lint
+
+lint: tools
+	$(GOBIN)/golangci-lint run ./...
+
 generate:
 	go generate ./...