chore: get-regexp is deprecated

[Rudxain]

According to the docs, config --get-regexp is deprecated in favor of config get --all --show-names --regexp, so I replaced all the occurrences I've found

[spacewander]

git config get raises the runtime requirement to Git 2.46+. The new git config subcommands were introduced with Git 2.46, while older supported/system Git versions, for example Apple Git 2.39.5, reject git config get --all --show-names --regexp ... with usage output.

Let's keep the old one. Does git have a plan to drop the get-regexp?

[Rudxain]

raises the runtime requirement to Git 2.46+

oh :(

Does git have a plan to drop the get-regexp?

According to v3.0 docs, not yet, so I guess this PR can be closed