syft attest cmd is not exporting output to file

[developer-guy]

What happened:

What you expected to happen:

We (w/@Dentrax) noticed that Syft attest command has a --file option to redirect the output o a file but this feature is not working.

To reproduce an issue run the following commands:

$ syft atttest --key <key> <img>  -o json --file att.json
$ cat att.json
'att.json': No such file or directory (os error 2)

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know?:

Environment:

• Output of syft version: 0.48.1
• OS (e.g: cat /etc/os-release or similar):

[spiffcs]

👋 Hi Developer guy:

When you run something lime syft attest --key cosign.key -o json alpine:latest > attest.json and redirect the output you can write to a file.

I know for the SBOM we have the --file option. Would you like to see this flag added on attestation as well?

[developer-guy]

Yep, I know this is my workaround too I redirected to a file through the > operator. But yeah, it'd be better to support the --file option for attestation as well, would you mind assigning it to me?

[spiffcs]

Sure - stabilizing the surfaces would be awesome to get some consistency between the commands:
cc @anchore/ci-tools-project if anyone has a different opinion on this issue