Raise `TypeError` in pure Python `hmac.digest` for non-bytes keys

Bug report

Bug description:

hmac.digest() reaches key.ljust() with a key type its own class rejects by name, so hmac.digest(memoryview(key), msg, "md5") raises AttributeError instead of TypeError as hmac.HMAC does. I'm aligning the exceptions here but I may consider accepting other types later.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-155427