.github: update workflows to use flake.nix go version etc

And also run lints.

This is cribbed from the ngrok-go repo

.envrc

@@ -0,0 +1,7 @@
+if ! has nix_direnv_version || ! nix_direnv_version 2.2.0; then
+  source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/2.2.0/direnvrc" "sha256-5EwyKnkJNQeXrRkYbwwRBcXbibosCJqyIUuz9Xq+LRc="
+fi
+dotenv_if_exists
+GOPATH=`pwd`/.direnv/go
+PATH=${GOPATH}/bin:${PATH}
+use flake

.github/workflows/lint.yml

@@ -0,0 +1,30 @@
+name: lint
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+permissions:
+  contents: read
+  # Optional: allow read access to pull request. Use with `only-new-issues` option.
+  # pull-requests: read
+jobs:
+  lint:
+    name: lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 2
+      - uses: cachix/install-nix-action@v18
+      - uses: HatsuneMiku3939/direnv-action@v1
+      - name: direnv allow
+        run: direnv allow .
+      - name: Run goimports
+        shell: bash
+        run: direnv exec . goimports -format-only -w -local github.com/ngrok/tableroll **/*.go
+      - name: Lint
+        run: direnv exec . golangci-lint run .
+      - name: Check diff
+        shell: bash
+        run: git diff --exit-code

.github/workflows/test.yml

@@ -0,0 +1,22 @@
+name: Go
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+jobs:
+  build-and-test:
+    runs-on: ubuntu-latest
+    env:
+      NGROK_TEST_ONLINE: 1
+      NGROK_TEST_LONG: 1
+      NGROK_TEST_FLAKEY: 1
+      NGROK_AUTHTOKEN: ${{ secrets.NGROK_AUTHTOKEN }}
+    steps:
+    - uses: actions/checkout@v3
+    - uses: cachix/install-nix-action@v18
+    - uses: HatsuneMiku3939/direnv-action@v1
+    - name: direnv allow
+      run: direnv allow .
+    - name: Test
+      run: direnv exec . go test -v ./...

.gitignore

@@ -0,0 +1 @@
+/.direnv

dup_file.go

@@ -1,3 +1,4 @@
+//go:build go1.12
 // +build go1.12
 
 package tableroll

dup_file_legacy.go

@@ -1,3 +1,4 @@
+//go:build !go1.12
 // +build !go1.12
 
 package tableroll