Add priority to gotify channel

Closes: #1277

modules/notification/api/src/main/scala/docspell/notification/api/Channel.scala

@@ -53,7 +53,12 @@ object Channel {
       deriveConfiguredEncoder[Mail]
   }
 
-  final case class Gotify(id: Ident, url: LenientUri, appKey: Password) extends Channel {
+  final case class Gotify(
+      id: Ident,
+      url: LenientUri,
+      appKey: Password,
+      priority: Option[Int]
+  ) extends Channel {
     val channelType = ChannelType.Gotify
     def fold[A](
         f1: Mail => A,

modules/notification/api/src/main/scala/docspell/notification/api/NotificationChannel.scala

@@ -30,7 +30,8 @@ object NotificationChannel {
       headers: Map[String, String]
   ) extends NotificationChannel
 
-  final case class Gotify(url: LenientUri, appKey: Password) extends NotificationChannel
+  final case class Gotify(url: LenientUri, appKey: Password, priority: Option[Int])
+      extends NotificationChannel
 
   final case class Matrix(
       homeServer: LenientUri,

modules/notification/impl/src/main/scala/docspell/notification/impl/GotifyBackend.scala

@@ -35,6 +35,7 @@ final class GotifyBackend[F[_]: Async](
       val req = POST(
         Json.obj(
           "title" -> Json.fromString(title),
+          "priority" -> Json.fromInt(channel.priority.getOrElse(0)),
           "message" -> Json.fromString(body),
           "extras" -> Json.obj(
             "client::display" -> Json.obj(