Fix source and update sha256 for gmp 6.3.0

[GuillaumeGomez]

As rightfully detected in #17 (comment) by @thesamesam, this was the wrong source. I updated the hash as well.

[Kobzol]

Could you create a new entry please? We want to document all files in mirrors. The old one will stay there as legacy.

[GuillaumeGomez]

Yeah but the content is wrong. It's not .bz2 and it was never used. Do we want to keep the current invalid one?

[Kobzol]

If it's on the mirrors, it should be in the TOML file. We don't have a way of removing files from mirrors automatically, I think. @pietroalbini ?

[marcoieni]

Sorry, approved without reading the comments.

[GuillaumeGomez]

Can it be done manually? :3

[Kobzol]

Yeah, but I'm not sure if it's worth the effort. We have hundreds of legacy and unused files in the mirrors anyway.

[GuillaumeGomez]

Considering it's the same file name, I hope it won't create issues...

[pietroalbini]

Creating a new file with the same name as an existing file will not work, intentionally. The best option is to call the file something else.

[GuillaumeGomez]

Yeah except we can't do that. It's this file that the script is trying to download, hence why I asked if it's possible to remove it manually because we're kinda stuck here.

[Kobzol]

@marcoieni Could you please remove the previously uploaded file manually?

[marcoieni]

deleting these two files

[marcoieni]

deleted the previous files. Merging this PR now

[GuillaumeGomez]

No no no!

[marcoieni]

ok, it should be good now, sorry 😂

[GuillaumeGomez]

I confirm it is. Needed to revert to the original state of the PR. :)

[GuillaumeGomez]

Network flakyness issue? The URL does download the file for me.

[marcoieni]

works for me too, let's see..

[GuillaumeGomez]

Dark magic. Thanks!