Syft creates two LicenseRef- that differ only by case

**What happened**:

In the following file:
[syft-container5.spdx.json.txt](https://github.com/anchore/syft/files/12746483/syft-container5.spdx.json.txt)
Syft has created two LicenseRef- that differ only by case:
```
LicenseRef-BSD-3-clause-generic
```
```
LicenseRef-BSD-3-clause-GENERIC
```

This is invalid SPDX. See https://github.com/spdx/tools-java/issues/143

**What you expected to happen**:

Syft should create two distinct indentifiers.

**Steps to reproduce the issue**:

**Anything else we need to know?**:

**Environment**:
- Output of `syft version`: syft-0.86.1

Start with the attached syft-container5.spdx.json.txt and the reported syft-0.86.1 behavior. Reproduce the case-only LicenseRef variants and trace the SPDX output generation; done means the generated output no longer violates SPDX because identifiers differ only by case.

Written by the indexing model from the issue text.