fix: preserve license exceptions

[mikhailantoshkin]

fixes #303

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 78.57143% with 3 lines in your changes missing coverage. Please review.

Project coverage is 6.98%. Comparing base (b616135) to head (142491c). Report is 265 commits behind head on main.

Files with missing lines	Patch %	Lines
cargo-sbom/src/main.rs	0.00%	2 Missing :warning:
cargo-sbom/src/util/spdx/mod.rs	0.00%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff            @@
##             main    #304      +/-   ##
=========================================
- Coverage   12.94%   6.98%   -5.96%     
=========================================
  Files           7       5       -2     
  Lines         595     945     +350     
  Branches      595     945     +350     
=========================================
- Hits           77      66      -11     
- Misses        499     870     +371     
+ Partials       19       9      -10     

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[mikhailantoshkin]

looks like clippy is running 1.88 lints and getting angry