Consider using light weight downloader (e.g. `curl`) instead of `reqwest`

[luojia65]

Using large web framework is flexible and feature rich, but is somehow expensive in disk space. My matrix calculation program compiles intel-mkl-src whick requires a huge web framework by extern crate reqwest (code), resulting in eaten up almost 3.44GB of disk space only to calculate one dot result of two matrices. If we consider light weight framework e.g. curl, we can get rid of large target folder space cost and download the source faster (rather than GBs of target + source size).

[Shnatsel]

ureq is a fairly minimal alternative to reqwest. It is synchronous, so it does not pull in the huge tokio dependency.