Update sbt-microsites to 1.1.3 (#366)

Author: scala-steward

project/plugins.sbt

@@ -1,5 +1,5 @@
 addSbtPlugin("com.47deg"     % "sbt-org-policies" % "0.13.1")
-addSbtPlugin("com.47deg"     % "sbt-microsites"   % "1.1.2")
+addSbtPlugin("com.47deg"     % "sbt-microsites"   % "1.1.3")
 addSbtPlugin("com.eed3si9n"  % "sbt-buildinfo"    % "0.9.0")
 addSbtPlugin("org.scoverage" % "sbt-scoverage"    % "1.6.1")
 addSbtPlugin("org.scalameta" % "sbt-mdoc"         % "2.1.1")