Fix warnings in tests regarding \eps

[originalsouth]

Address the following warnings in the ] test Transformers environment:

┌ Warning: function crossentropy no longer accepts greek-letter keyword ϵ
│ please use ascii eps instead
│   caller = (::var"#_crossentropy#82"{var"#_crossentropy#29#83"})(::Matrix{Float32}, ::Vararg{Any}; kwargs::Base.Pairs{Symbol, Any, Tuple{Symbol, Symbol}, NamedTuple{(:dims, :agg), Tuple{Int64, var"#noagg#80"{var"#noagg#28#81"}}}}) at loss.jl:10
└ @ Main ~/.julia/packages/Transformers/qhUJm/test/loss.jl:10
┌ Warning: function crossentropy no longer accepts greek-letter keyword ϵ
│ please use ascii eps instead
│   caller = ip:0x0
└ @ Core :-1

[chengchingwen]

Thanks!