Add "Retrieve your token's bot user" endpoint

user.go

@@ -1,16 +1,38 @@
 package notion
 
+type UserType string
+
+const (
+	UserTypePerson UserType = "person"
+	UserTypeBot    UserType = "bot"
+)
+
 type Person struct {
 	Email string `json:"email"`
 }
 
-type Bot struct{}
+type Bot struct {
+	Owner BotOwner `json:"owner"`
+}
+
+type BotOwnerType string
+
+const (
+	BotOwnerTypeWorkspace BotOwnerType = "workspace"
+	BotOwnerTypeUser      BotOwnerType = "user"
+)
+
+type BotOwner struct {
+	Type      BotOwnerType `json:"type"`
+	Workspace bool         `json:"workspace"`
+	User      *User        `json:"user"`
+}
 
 type User struct {
-	ID        string  `json:"id"`
-	Type      string  `json:"type"`
-	Name      string  `json:"name"`
-	AvatarURL *string `json:"avatar_url"`
+	ID        string   `json:"id"`
+	Type      UserType `json:"type"`
+	Name      string   `json:"name"`
+	AvatarURL string   `json:"avatar_url"`
 
 	Person *Person `json:"person"`
 	Bot    *Bot    `json:"bot"`