t/unit-tests: update clar to 39f11fe

t/unit-tests: update clar to 39f11fe

Update clar to commit 39f11fe (Merge pull request #131 from
pks-gitlab/pks-integer-double-evaluation, 2025-12-05). This commit
includes the following changes relevant to Git:

  - There are now typesafe integer comparison functions. Furthermore,
    the range of comparison functions has been included to also have
    relative comparisons, like "greater than".

  - There is a new `cl_failf()` macro that allows the caller to specify
    an error message with formatting directives.

  - The TAP format has been fixed to correctly terminate YAML blocks
    with "...\n" instead of "---\n".

Note that we already had a `cl_failf()` function declared in our own
sources. This function is equivalent to the upstreamed function, so we
can simply drop it now.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>