[scala-3] Default implementation for type Writer[A] and Reader[A]

gets rid of compilation error

branch: feature/scala-3.3.x

Author: SamTheisens

core/src/main/scala/api/SerializationPack.scala

@@ -7,15 +7,15 @@ import scala.util.Try
 import scala.reflect.ClassTag
 
 import reactivemongo.core.protocol.Response
-
+import reactivemongo.api.bson.{ BSONDocumentReader, BSONDocumentWriter }
 import reactivemongo.api.bson.buffer.{ ReadableBuffer, WritableBuffer }
 
 trait SerializationPack extends SerializationPackCompat { self: Singleton =>
   type Value
   type ElementProducer
   type Document <: Value
-  type Writer[A]
-  type Reader[A]
+  type Writer[A] = BSONDocumentWriter[A]
+  type Reader[A] = BSONDocumentReader[A]
   type NarrowValueReader[A]
   private[reactivemongo] type WidenValueReader[A]
 

project/Common.scala

@@ -53,7 +53,7 @@ object Common extends AutoPlugin {
 
   override def projectSettings =
     Defaults.coreDefaultSettings ++ baseSettings ++ Compiler.settings ++ Seq(
-      scalaVersion := "2.12.18",
+      scalaVersion := scala31,
       crossScalaVersions := Seq(
         scala211,
         scalaVersion.value,