lists.wm.org - raise HSTS max-age to 1 year

Patch I53f27e7d enabled HTTP Strict Transport Security
and set its max-age to 7 days. This patch raises the
max-age to 1 year (365 days).

Still, I don't believe an increased HSTS max-age could
cause any problems in the server's functionality, as
long as we keep supporting HTTPS. A related discussion
is on Ic3062981.

Bug: 38516
Change-Id: I45ac77e1e0bc2dda6e17f577ea9b9927d2af177e