Replace gogs/cron with go-co-op/gocron (#25977)

Replace `github.com/gogs/cron` with `github.com/go-co-op/gocron` as the
former package is not maintained for many years.

---------

Co-authored-by: delvh <dev.lh@web.de>

services/cron/tasks_test.go

@@ -0,0 +1,61 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package cron
+
+import (
+	"strconv"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAddTaskToScheduler(t *testing.T) {
+	assert.Len(t, scheduler.Jobs(), 0)
+	defer scheduler.Clear()
+
+	// no seconds
+	err := addTaskToScheduler(&Task{
+		Name: "task 1",
+		config: &BaseConfig{
+			Schedule: "5 4 * * *",
+		},
+	})
+	assert.NoError(t, err)
+	assert.Len(t, scheduler.Jobs(), 1)
+	assert.Equal(t, "task 1", scheduler.Jobs()[0].Tags()[0])
+	assert.Equal(t, "5 4 * * *", scheduler.Jobs()[0].Tags()[1])
+
+	// with seconds
+	err = addTaskToScheduler(&Task{
+		Name: "task 2",
+		config: &BaseConfig{
+			Schedule: "30 5 4 * * *",
+		},
+	})
+	assert.NoError(t, err)
+	assert.Len(t, scheduler.Jobs(), 2)
+	assert.Equal(t, "task 2", scheduler.Jobs()[1].Tags()[0])
+	assert.Equal(t, "30 5 4 * * *", scheduler.Jobs()[1].Tags()[1])
+}
+
+func TestScheduleHasSeconds(t *testing.T) {
+	tests := []struct {
+		schedule  string
+		hasSecond bool
+	}{
+		{"* * * * * *", true},
+		{"* * * * *", false},
+		{"5 4 * * *", false},
+		{"5 4 * * *", false},
+		{"5,8 4 * * *", false},
+		{"*   *   *  * * *", true},
+		{"5,8 4   *  *   *", false},
+	}
+
+	for i, test := range tests {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
+			assert.Equal(t, test.hasSecond, scheduleHasSeconds(test.schedule))
+		})
+	}
+}