Use db.provider in example projects

[timleslie]

db.adapter is now deprecated, so this converts the example projects to use the new db.provider option.

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🦋 Changeset detected

Latest commit: f84f35f

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 8 packages

Name	Type
@keystone-next/example-auth	Patch
@keystone-next/app-basic	Patch
@keystone-next/example-ecommerce	Patch
keystone-next-app	Patch
@keystone-next/example-next-lite	Patch
@keystone-next/example-roles	Patch
@keystone-next/example-sandbox	Patch
@keystone-next/example-todo	Patch

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