test: add e2e tests with local Forgejo instance (#201)

* feat(forge): add new forge for forgejo

We only support repositories hosted on Forgejo instances, but not
Forgejo Actions or Woodpecker as CI solutions for now.

* test(e2e): introduce e2e test framework with local forgejo

test/e2e/forgejo/forgejo_test.go

@@ -0,0 +1,39 @@
+//go:build e2e_forgejo
+
+package forgejo
+
+import (
+	"context"
+	"log/slog"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/apricote/releaser-pleaser/test/e2e"
+)
+
+var (
+	f *e2e.Framework
+)
+
+func TestMain(m *testing.M) {
+	ctx := context.Background()
+
+	var err error
+	f, err = e2e.NewFramework(ctx, &TestForge{})
+	if err != nil {
+		slog.Error("failed to set up test framework", "err", err)
+	}
+
+	os.Exit(m.Run())
+}
+
+func TestCreateRepository(t *testing.T) {
+	_ = f.NewRepository(t, t.Name())
+}
+
+func TestRun(t *testing.T) {
+	repo := f.NewRepository(t, t.Name())
+	require.NoError(t, f.Run(t, repo, []string{}))
+}