message: futures is a optional dependecy only needed by api and runtime
diff: @@ -19,7 +19,7 @@ derive-new = { version = "0.5.9", optional = true }
  ed25519-dalek = { version = "1.0", optional = true }
  floating-duration = { version = "0.1.2", optional = true }
  fs_extra = { version = "1.2", optional = true }
  -futures = "0.3.14"
  +futures = { version = "0.3.14", optional = true }
  hex = { version = "0.4.3", optional = true }
  humanize-rs = { version = "0.1.5", optional = true }
  itertools = { version = "0.10.0", optional = true }
  @@ -56,6 +56,7 @@ proptest = "1.0"
  api = [
  "bytes",
  "derive-new",
  + "futures",
  "npk",
  "serde_json",
  "tokio-util",
  @@ -88,6 +89,7 @@ runtime = [
  "caps",
  "ed25519-dalek",
  "floating-duration",
  + "futures",
  "hex",
  "itertools",
  "lazy_static",
  