tour: update to the App Engine Go 1.14 runtime
tour: update to the App Engine Go 1.14 runtime

Reference:

•	https://cloud.google.com/appengine/docs/standard/go/runtime

Change-Id: I46b87098ed04c9c5d9f84193c9d72f9d30a59233
Reviewed-on: https://go-review.googlesource.com/c/tour/+/266818
Trust: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
Run-TryBot: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
TryBot-Result: Go Bot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Alexander Rakoczy <60c6d277a8bd81de7fdde19201bf9c58a3df08f4@golang.org>
Reviewed-by: Carlos Amedee <ab5e2bca84933118bbc9d48ffaccce3bac4eeb64@golang.org>

zorion/go-tour-ca,zorion/go-tour-ca,golang/tour