Automate the Hugo release process

This commit adds a work flow aroung GoReleaser to get the Hugo release process automated and more uniform:

* It can be run fully automated or in two steps to allow for manual edits of the relase notes.
* It supports both patch and full releases.
* It fetches author, issue, repo info. etc. for the release notes from GitHub.
* The file names produced are mainly the same as before, but we no use tar.gz as archive for all Unix versions.
* There isn't a fully automated CI setup in place yet, but the release tag is marked in the commit message with "[ci deploy]"

Fixes #3358

releaser/github_test.go

@@ -0,0 +1,42 @@
+// Copyright 2017-present The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package releaser
+
+import (
+	"fmt"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestGitHubLookupCommit(t *testing.T) {
+	skipIfNoToken(t)
+	commit, err := fetchCommit("793554108763c0984f1a1b1a6ee5744b560d78d0")
+	require.NoError(t, err)
+	fmt.Println(commit)
+}
+
+func TestFetchRepo(t *testing.T) {
+	skipIfNoToken(t)
+	repo, err := fetchRepo()
+	require.NoError(t, err)
+	fmt.Println(">>", len(repo.Contributors))
+}
+
+func skipIfNoToken(t *testing.T) {
+	if os.Getenv("GITHUB_TOKEN") == "" {
+		t.Skip("Skip test against GitHub as no GITHUB_TOKEN set.")
+	}
+}