- Update Dockerfile from 1.13 to 1.16
- Update GitHub Actions from 1.14 to 1.16

Updated vendor directory according to:

```
go: inconsistent vendoring in /Users/bflad/src/github.com/bflad/tfproviderlint:
	github.com/bflad/[email protected]: is explicitly required in go.mod, but not marked as explicit in vendor/modules.txt
	github.com/hashicorp/[email protected]: is explicitly required in go.mod, but not marked as explicit in vendor/modules.txt
	github.com/hashicorp/terraform-plugin-sdk/[email protected]: is explicitly required in go.mod, but not marked as explicit in vendor/modules.txt
	golang.org/x/[email protected]: is explicitly required in go.mod, but not marked as explicit in vendor/modules.txt

	To ignore the vendor directory, use -mod=readonly or -mod=mod.
	To sync the vendor directory, run:
		go mod vendor
```

* deps: Bump github.com/hashicorp/terraform-plugin-sdk/[email protected]

Updated via:

```
go get github.com/hashicorp/terraform-plugin-sdk/[email protected]
go mod tidy
go mod vendor
```

* deps: Bump github.com/hashicorp/terraform-plugin-sdk@v1-maint

To prevent `go-getter` errors.

Updated via:

```
go get github.com/hashicorp/terraform-plugin-sdk@v1-maint
go mod tidy
go mod vendor
```

* New Extra Check: XAT001: check for TestCase missing ErrorCheck

Reference: #226