If `git` is configured to open an editor on commit (to edit a commit
message), it adds a `git diff` below the scissor line. Tell `typos`
to ignore everything below it.
Commit messages in the CMake repo may have Git hashes that can trigger
false positives in the `typos` checker.
Revert commit ddebf4653d (ci: Do not check commit messages with 'typos'
due to false positives, 2025-02-07). Instead, copy the top-level config
file to a temporary location, add a configuration option to mark
10-hex-digit identifiers as always valid, and pass it to `typos` at the
commit checking phase.