message: bump env_logger to a more minimal-versions compatible one
diff: @@ -22,7 +22,7 @@ crates-io = { path = "src/crates-io", version = "0.18" }
  crossbeam-utils = "0.5"
  crypto-hash = "0.3.1"
  curl = "0.4.13"
  -env_logger = "0.5.4"
  +env_logger = "0.5.11"
  failure = "0.1.2"
  filetime = "0.2"
  flate2 = "1.0"
  