Update Scala 3 doc test

Current test depends on JCenter.

sbt-app/src/sbt-test/actions/doc-scala3/build.sbt

@@ -1,11 +1,9 @@
-lazy val m3 = (project in file("m3"))
-  .settings(
-    scalaVersion := "3.0.0-M3",
-    resolvers += Resolver.JCenterRepository
-  )
-
 lazy val rc1 = (project in file("rc1"))
   .settings(
     scalaVersion := "3.0.0-RC1"
   )
 
+lazy val a = project
+  .settings(
+    scalaVersion := "3.4.2",
+  )

sbt-app/src/sbt-test/actions/doc-scala3/test

@@ -6,10 +6,10 @@ $ exists rc1/target/scala-3.0.0-RC1/api/api/index.html
 $ exists rc1/target/scala-3.0.0-RC1/api/api/foo/A$.html
 $ exists rc1/target/scala-3.0.0-RC1/api/api/foo.html
 
-> m3 / doc
+> a / doc
 
 # there shouldn't be two api/ directories
 # see https://github.com/lampepfl/dotty/issues/11412
-$ exists m3/target/scala-3.0.0-M3/api/index.html
-$ exists m3/target/scala-3.0.0-M3/api/api/foo/A$.html
-$ exists m3/target/scala-3.0.0-M3/api/api/foo.html
+$ exists a/target/scala-3.4.2/api/index.html
+$ exists a/target/scala-3.4.2/api/foo/A$.html
+$ exists a/target/scala-3.4.2/api/foo.html