Avoid curl_easy_setopt error logs

[Manangka]

Due to an issue between the curl and openssl libraries the pixi run build tasks failed.
In JuliaLang/Downloads.jl#244 the cause of the issue is gfound to be environment variables being set that conflict.
This commit adds an environment variable to the tasks failing, clearing the SSL variables

[visr]

@Manangka closed this since the codegen failed, looks like juliaup fails to download with this. The error log this fixes is harmless, but looks scary, so I'm re-opening to see if we can use this.

See also #1644