Support cache (#25)

See [Caching dependencies to speed up workflows](https://docs.github.com/en/actions/using-workflows/caching-dependencies-to-speed-up-workflows).

Reviewed-on: https://gitea.com/gitea/act_runner/pulls/25
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Reviewed-by: Zettat123 <zettat123@noreply.gitea.io>
Co-authored-by: Jason Song <i@wolfogre.com>
Co-committed-by: Jason Song <i@wolfogre.com>

artifactcache/model.go

@@ -0,0 +1,30 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package artifactcache
+
+import (
+	"fmt"
+	"net/http"
+)
+
+type Cache struct {
+	ID        int64  `xorm:"id pk autoincr" json:"-"`
+	Key       string `xorm:"TEXT index unique(key_version)" json:"key"`
+	Version   string `xorm:"TEXT unique(key_version)" json:"version"`
+	Size      int64  `json:"cacheSize"`
+	Complete  bool   `xorm:"index(complete_used_at)" json:"-"`
+	UsedAt    int64  `xorm:"index(complete_used_at) updated" json:"-"`
+	CreatedAt int64  `xorm:"index created" json:"-"`
+}
+
+// Bind implements render.Binder
+func (c *Cache) Bind(_ *http.Request) error {
+	if c.Key == "" {
+		return fmt.Errorf("missing key")
+	}
+	if c.Version == "" {
+		return fmt.Errorf("missing version")
+	}
+	return nil
+}