.travis.yml: Remove the unused xfslib-dev package

Drop the "xfslibs-dev" package which should not be necessary anymore
since commit a5730b8 ("block/file-posix: Simplify the XFS_IOC_DIOINFO
handling").

Message-ID: <20240320104144.823425-3-thuth@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

.travis.yml

@@ -220,7 +220,6 @@ jobs:
           - libsnappy-dev
           - libzstd-dev
           - nettle-dev
-          - xfslibs-dev
           - ninja-build
           # Tests dependencies
           - genisoimage