rm simple unpack dependency from example env

Author: zuhengxu

example/Project.toml

@@ -16,7 +16,6 @@ Optimisers = "3bd65402-5787-11e9-1adc-39752487f4e2"
 Plots = "91a5bcdd-55d7-5caf-9e0b-520d859cae80"
 ProgressMeter = "92933f4c-e287-5a05-a399-4b506db050ca"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
-SimpleUnPack = "ce78b400-467f-4804-87d8-8f486da07d0a"
 StatsBase = "2913bbd2-ae8a-5f71-8c99-4fb6c76f3a91"
 
 [extras]