no need to set the certificates on 1.6+

[visr]

Should fix yeesian/ArchGDAL.jl#200

[visr]

This doesn't work on Linux for julia 1.6+, throwing a "CURL error: Cert verify failed: BADCERT_NOT_TRUSTED"

I also found this comment: JuliaLang/julia#39289 (comment).

Though it is probably preferable to just use https://github.com/JuliaLang/NetworkOptions.jl, and remove the MozillaCACerts_jll dependency, for all julia versions. NetworkOptions also installs on older julia versions. Quickly reading the README, it seems we could call ca_roots, and set it with cplsetconfigoption if the result is not nothing.

EDIT: NetworkOptions works, with the addition that on older julia versions we should use ca_roots_path instead, such that the bundled certificates are used on Windows and macOS, because otherwise it doesn't work.