Sync language.scala with main

Author: Kordyjan

library/src/scala/runtime/stdLibPatches/language.scala

@@ -246,6 +246,20 @@ object language:
   @compileTimeOnly("`3.4` can only be used at compile time in import statements")
   object `3.4`
 
+  /** Set source version to 3.5-migration.
+    *
+    * @see [[https://docs.scala-lang.org/scala3/guides/migration/compatibility-intro.html]]
+    */
+  @compileTimeOnly("`3.5-migration` can only be used at compile time in import statements")
+  object `3.5-migration`
+
+  /** Set source version to 3.5
+    *
+    * @see [[https://docs.scala-lang.org/scala3/guides/migration/compatibility-intro.html]]
+    */
+  @compileTimeOnly("`3.5` can only be used at compile time in import statements")
+  object `3.5`
+
   // !!! Keep in sync with dotty.tools.dotc.config.SourceVersion !!!
   // Also add tests in `tests/pos/source-import-3-x.scala` and `tests/pos/source-import-3-x-migration.scala`