[Buildroot] [PATCH:LTS] suport/docker: update the strech image

[Peter Korsgaard]

>>>>> "Yann" == Yann E MORIN <yann.morin.1998 at free.fr> writes:

 > The current stretch image we are usign on the maintenance branches still
 > has the old Let's Encrypt certificate that expired a few weeks ago,
 > causign a lot of download errors:

 > Suggested-by: Peter Korsgaard <peter at korsgaard.com>
 > Signed-off-by: Yann E. MORIN <yann.morin.1998 at free.fr>
 > Cc: Romain Naour <romain.naour at gmail.com>
 > ---
 > Note: when this is accepted, I'll regenerate and push a new image to the
 > docker hub, and send an new patch to use that image.

Committed to 2021.02.x and 2021.08.x, thanks.

-- 
Bye, Peter Korsgaard