`null_data_source` is depricated in Terraform

```
chalice --version
chalice 1.26.4, python 3.8.3, linux 5.11.0-41-generic
```

```
terraform --version
Terraform v1.0.11
on linux_amd64
+ provider registry.terraform.io/hashicorp/aws v3.72.0
+ provider registry.terraform.io/hashicorp/null v3.1.0
+ provider registry.terraform.io/hashicorp/template v2.2.0

Your version of Terraform is out of date! The latest version
is 1.1.4. You can update by downloading from https://www.terraform.io/downloads.html
```

If I run `terraform validate` on the TF output from Chalice I get:

```
terraform validate
╷
│ Warning: Deprecated Resource
│
│ with module.chalice.data.null_data_source.chalice,
│ on chalice/chalice.tf.json line 99, in data.null_data_source.chalice:
│ 99: }
│
│ The null_data_source was historically used to construct intermediate values to re-use elsewhere in configuration, the same can now be achieved using locals
╵
Success! The configuration is valid, but there were some validation warnings as shown above.

```

Reproduce the warning with Chalice 1.26.4 and the generated chalice/chalice.tf.json, then trace where the null_data_source configuration is produced. Check the generated Terraform with terraform validate; done means the output remains valid without the deprecated-resource warning.

Written by the indexing model from the issue text.