patchci: update FreeBSD image to 14.3

> From: =?UTF-8?q?Carlo=20Marcelo=20Arenas=20Bel=C3=B3n?= <carenas@gmail.com>
>
> FreeBSD 13.4 is no longer supported, and 13.5 will be the last
> release from that series, so jump instead to 14.3 which should
> be supported for another 10 months and will be at that point
> the oldest supported release with the interim release of 15.
>
> While at it, move some variables to the environment and make
> sure to skip a git grep test that assumes glibc regex.
>
> Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
> ---
>     ci: update FreeBSD image to 14.3
>
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2006%2Fcarenas%2Fmaster-v1
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2006/carenas/master-v1
> Pull-Request: https://github.com/git/git/pull/2006

>
>  .cirrus.yml | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/.cirrus.yml b/.cirrus.yml
> index 1fbdc2652b3..fef04a38402 100644
> --- a/.cirrus.yml
> +++ b/.cirrus.yml
> @@ -5,11 +5,13 @@ freebsd_task:
>    env:
>      GIT_PROVE_OPTS: "--timer --jobs 10"
>      GIT_TEST_OPTS: "--no-chain-lint --no-bin-wrappers"
> -    MAKEFLAGS: "-j4"
> +    GIT_SKIP_TESTS: t7815.12
> +    MAKEFLAGS: -j4
>      DEFAULT_TEST_TARGET: prove
> +    DEFAULT_UNIT_TEST_TARGET: unit-tests-prove
>      DEVELOPER: 1
>    freebsd_instance:
> -    image_family: freebsd-13-4
> +    image_family: freebsd-14-3
>      memory: 2G
>    install_script:
>      pkg install -y gettext gmake perl5
> @@ -19,4 +21,4 @@ freebsd_task:
>    build_script:
>      - su git -c gmake
>    test_script:
> -    - su git -c 'gmake DEFAULT_UNIT_TEST_TARGET=unit-tests-prove test unit-tests'
> +    - su git -c 'gmake test unit-tests'
>
> base-commit: 83014dc05f6fc9275c0a02886cb428805abaf9e5