Add minimal linter config to enforce gofumpt

Author: flimzy

.github/workflows/lint.yaml

@@ -0,0 +1,25 @@
+name: golangci-lint
+on:
+  pull_request:
+permissions:
+  contents: read
+jobs:
+  golangci:
+    name: lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+
+      - uses: actions/setup-go@v3
+        with:
+          go-version: "1.18.10"
+
+      - name: golangci-lint
+        uses: golangci/golangci-lint-action@v3
+        with:
+          version: v1.53.3
+          only-new-issues: true
+
+      - name: Check go.mod
+        run: |
+          go mod tidy && git diff --exit-code

.golangci.toml

@@ -0,0 +1,14 @@
+[run]
+timeout = "1m"
+
+[output]
+format = "colored-line-number"
+
+[linters]
+disable-all = true
+enable = [
+    "gofumpt",
+]
+
+[issues]
+exclude-use-default = false

circle.yml

@@ -72,9 +72,6 @@ jobs:
     executor: gopherjs
     steps:
     - setup_and_install_gopherjs
-    - run:
-        name: Check gofmt
-        command: diff -u <(echo -n) <(gofmt -d .)
     - run:
         name: Check go vet
         command: |