Add ability to ignore/exclude directories

[kzantow]

Running sbom-action against Syft there is the possibility that using an older version of Syft will cause failures - in particular with newer or intentionally failing test fixtures, as seen here: https://github.com/anchore/syft/runs/3967971554?check_suite_focus=true#step:11:119 (discussion here: https://anchorecommunity.slack.com/archives/C4PJFNEEM/p1634844391026300).

[yonas]

@kzantow This is what I'm looking for 👍

[kzantow]

@yonas you should be able to use the SYFT_EXCLUDE environment variable for this action, which accepts a comma-separated list of directories. E.g. for your example, I think this should work:

      - uses: anchore/sbom-action@latest
        env:
          SYFT_EXCLUDE: ./target