Fix regression in #14546

[DarkaMaul]

In #14546, I extracted _version_key from get_remote_latest_tag and reused it in get_current_version_from_file to pick the minimum version among multiple matches.

However, _version_key parses dotted version strings as integer tuples, which fails on commit SHAs like BoringSSL, which caused the regression here

The new algorithm is simpler:

• Identify the latest version
• Identify all versions present in the file
• If there is at least one which is not the latest, update them all

[DarkaMaul]

FLAG: This will produce a slightly incorrect commit message if we have multiple versions we need to update, but I think adding trhe logic to find the oldest commit is not worth the extra complexity.