Dockerfile: pin git-lfs version to 2.5.*
Dockerfile: pin git-lfs version to 2.5.*

git-lfs 2.6.0 released last week contains a bug that causes all qtauto
builds to hang indefinitely.

git lfs pull was added in pelagicore/meta-pelux@fe2ce6fb25a34d07f7db .

Signed-off-by: Martin Ejdestig <6245dcb10f19f01f215dad2c1bc577b6938fd827@luxoft.com>

Pelagicore/pelux-manifests,sashko/pelux-manifests