Bump version of reference documentation to 3.1.3

Author: Kordyjan

project/Build.scala

@@ -1413,7 +1413,7 @@ object Build {
             .add(OutputDir("scaladoc/output/reference"))
             .add(SiteRoot(s"${temp.getAbsolutePath}/docs"))
             .add(ProjectName("Scala 3 Reference"))
-            .add(ProjectVersion("3.1.2")) // TODO: Change that later to the current version tag. (This must happen on first forward this branch to stable release tag)
+            .add(ProjectVersion("3.1.3")) // TODO: Change that later to the current version tag. (This must happen on first forward this branch to stable release tag)
             .remove[VersionsDictionaryUrl]
             .add(SourceLinks(List(
               s"${temp.getAbsolutePath}=github://lampepfl/dotty/language-reference-stable"