style: ensure that files terminate with empty new line using `pre-commit`

As mentioned on https://stackoverflow.com/questions/729692/why-should-text-files-end-with-a-newline and https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_206, POSIX defines a line as

A sequence of zero or more non- characters plus a terminating character.

When a file does not terminate with an empty line, Git commands such as git diff show the message No newline at end of file.

This commit adds a CI job pre-commit to enforce the formatting.