bump minimum postgres version warning to 9.5
bump minimum postgres version warning to 9.5

Change-Id: Ib3d5aeaf5e5263fb313909b570e10cab5a012c61
Reviewed-on: https://gerrit.instructure.com/152270
Tested-by: Jenkins
Reviewed-by: Jeremy Neander <20252aad5efdc666f083d82ab63ed0f9f72a043e@instructure.com>
Product-Review: Neil Gupta <cc4fec8a34766005dd45d48be045c08d736c11ed@instructure.com>
QA-Review: Neil Gupta <cc4fec8a34766005dd45d48be045c08d736c11ed@instructure.com>

sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,djbender/canvas-lms