Incorrect license is not detected/fixed

It appears the `copywrite` will not detect or attempt to fix wrong license, for example in `hashicorp/terraform`:

If I attempt to change `provider_source.go` in root to contain
```go
// SPDX-License-Identifier: MPL-2.0
```

```
$ copywrite headers
Using license identifier: BUSL-1.1
Using copyright holder: HashiCorp, Inc.

Exempting the following search patterns:
**/*.tf
**/testdata/**
**/*.pb.go
**/*_string.go
**/mock*.go
docs/plugin-protocol/**
internal/tfplugin*/**

The following files are missing headers:
```
```
$ head -2 provider_source.go
// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0
```