Fix CI compile errors

internal/util-complete/src/test/scala/ParserTest.scala

@@ -18,7 +18,7 @@ object JLineTest {
   val four = token("color" ~> Space) ~> token(ID, "<color name>")
 
   val num = token(NatBasic)
-  val five = (num ~ token("+" | "-") ~ num) <~ token('=') flatMap {
+  val five = (num ~ token("+" | "-") ~ num) <~ token('=') collect {
     case a ~ "+" ~ b => token((a + b).toString)
     case a ~ "-" ~ b => token((a - b).toString)
   }

main-actions/src/main/scala/sbt/Pkg.scala

@@ -22,7 +22,6 @@ import sjsonnew.{
   LNil,
   Unbuilder,
   deserializationError,
-  flatUnionFormat4
 }
 
 import sbt.util.Logger

main-settings/src/test/scala/sbt/TupleSyntaxTest.scala

@@ -9,7 +9,6 @@
 package sbt.test
 
 import sbt._
-import sbt.Def.Initialize
 
 object TupleSyntaxTest:
   def t1[A](a: SettingKey[A], b: TaskKey[A], c: Def.Initialize[A], d: Def.Initialize[Task[A]]) = {

main-settings/src/test/scala/sbt/std/UsageTest.scala

@@ -32,7 +32,6 @@ end UseTask
 object Assign {
   import java.io.File
 
-  import sbt.std.FullInstance.given
   import Def.{
     Initialize,
     inputKey,