Update zio, zio-streams, zio-test, ... to 2.0.21 (#1360)

build.sbt

@@ -22,7 +22,7 @@ val V = new {
   val slf4j              = "2.0.9"
   val sttp               = "3.9.1"
   val vulcan             = "1.10.1"
-  val zio                = "2.0.19"
+  val zio                = "2.0.21"
   val `zio-interop`      = "23.0.0.8"
   val `zio-json`         = "0.6.2"
   val `zio-kafka`        = "2.6.0"