Fix Dependabot by removing npm engine-strict=true

The Node.js LTS v20 update in #4201 has stopped Dependabot from running

Rather than allow Node.js v18 and npm v9.6.5 we can remove `engine-strict=true`

```
Dependabot uses Node.js v18.18.2
 and NPM 9.6.5
. Due to the engine-strict setting, the update will not succeed.
```