Make sure that every repo URL ends in a trailing .git (except for repos hosted on Sourcehut)

[DilumAluthge]

In the registry, our convention is for every repo URL to end in a trailing .git. This PR makes sure that every URL adheres to the convention. Except for repos hosted on Sourcehut (git.sr.ht), which doesn't seem to support URLs with the trailing .git.

Future work:

• Add a CI check to enforce this (RegistryCI: require package repo URLs to end in .git (except for repos hosted on Sourcehut) RegistryCI.jl#671)

This PR was generated by the following Julia script:

import TOML

for (path, _, files) in walkdir(".")
    sort_order = Dict(
        "name" => 1,
        "uuid" => 2,
        "repo" => 3,
        "subdir" => 4,
        "metadata" => 5,
        "reason" => 6,
        "alternative" => 7,
    )
    by_function = key -> sort_order[key]
    for file in files
        if file == "Package.toml"
            fullpath = joinpath(path, file)
            dict = TOML.parsefile(fullpath)
            haskey(dict, "repo") || @error "" fullpath dict
            if !endswith(dict["repo"], ".git")
                dict["repo"] = dict["repo"] * ".git"
            end
            open(fullpath, "w") do io
                TOML.print(io, dict; sorted = true, by = by_function)
            end
        end
    end
end

I wrote this script by hand. No generative AI tools were used.