Update dependency org.scalameta:sbt-mdoc to v2.6.5

Author: renovate[bot]

project/plugins.sbt

@@ -1,5 +1,5 @@
 addSbtPlugin("com.github.sbt" % "sbt-site-paradox" % "1.5.0")
-addSbtPlugin("org.scalameta" % "sbt-mdoc" % "2.3.6")
+addSbtPlugin("org.scalameta" % "sbt-mdoc" % "2.6.5")
 addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.4.3")
 addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "1.1.3")
 addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.5.12")