failing to read ftp://ftp.ifremer.fr/ifremer/argo/dac/

It is reachable but very slow, so much so that the `readdir` command below just hangs and errors out. This used to work fine.

```
using ArgoData
import ArgoData.GDAC: FTP
import ArgoData.GDAC: DataFrames
files_list=DataFrames.DataFrame("folder" => [],"wmo" => [])
list_folders=readdir(ftp)
```

leading to this error message :

```
ERROR: Failed to list directories. :: LibCURL error #28
Stacktrace:
[1] macro expansion
@ ~/.julia/packages/FTPClient/7DJzC/src/FTPC.jl:62 [inlined]
[2] ftp_perform(ctxt::FTPClient.ConnContext{Bool})
@ FTPClient ~/.julia/packages/FTPClient/7DJzC/src/conn_context.jl:298
```

@gmaze , have you experienced this type of issue in argopy?