Update sbt-mdoc to 2.7.2 (#270)

Author: scala-steward

project/plugins.sbt

@@ -1,7 +1,7 @@
 addSbtPlugin("org.xerial.sbt" % "sbt-sonatype" % "3.12.2")
 addSbtPlugin("com.github.sbt" % "sbt-pgp"      % "2.3.1")
 addSbtPlugin("org.scalameta"  % "sbt-scalafmt" % "2.5.5")
-addSbtPlugin("org.scalameta"  % "sbt-mdoc"     % "2.7.1")
+addSbtPlugin("org.scalameta"  % "sbt-mdoc"     % "2.7.2")
 addSbtPlugin("com.github.sbt" % "sbt-release"  % "1.4.0")
 addSbtPlugin("com.github.sbt" % "sbt-git"      % "2.1.0")
 addSbtPlugin("com.github.sbt" % "sbt-protobuf" % "0.8.2")