internal/history: add Go 1.18
internal/history: add Go 1.18

Change-Id: I20f7bb73f453705fb45d3c914d6b48a66524c3a6
Reviewed-on: https://go-review.googlesource.com/c/website/+/392934
Trust: Heschi Kreinick <e89ab2b172855aa0ad01c40c4d8a3535a61ac68a@google.com>
Run-TryBot: Heschi Kreinick <e89ab2b172855aa0ad01c40c4d8a3535a61ac68a@google.com>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@google.com>

golang/website,golang/website,golang/website,golang/website,golang/website,golang/website,golang/website