message: Clarify Cargo.toml file a bit.
diff: @@ -22,7 +22,6 @@ serde_derive = "1.0"
  atty = "0.2.11"
  clap = { version = "2.32", default-features = false }
  csv = "1.0"
  -csv-core = "<0.1.5"
  walkdir = "2.2.7"
  tinytemplate = { version = "1.0.1", optional = true }
  cast = "0.2"
  @@ -31,6 +30,10 @@ rand_os = "0.1"
  rand_xoshiro = "0.1"
  rand_core = { version = "0.3", default-features = false }
  rayon = "1.0.3"
  +
  +# This is needed to build on old rustc versions.
  +csv-core = "<0.1.5"
  +
  # These are needed for the minimal-versions build
  rayon-core = ">=1.4.1"
  libc = ">=0.1.5"
  