download.sh: add `--no-config` to all wget calls

[varenc]

This addresses an issue where wget would use the user's ~/.wgetrc file, which could cause problems if the user had configured wget to use certain user-agents. In general, ignoring the user's config seems like a good idea.

Issue I ran into specifically is here: https://github.com/facebookresearch/llama/issues/418#issuecomment-1644416221

[davidesn]

Great find! Thank you.