tests: Update CLI usage to match new JSON output option

Tests have been updated to reflect the new command-line interface.
The previous `--format json --output` options are replaced with the
`--json-output` option, matching the current tool behavior.

Signed-off-by: Christophe Guerreiro <christophe.guerreiro@non.se.com>

Author: Christophe Guerreiro

tests/helper.py

@@ -102,9 +102,7 @@ def _run_spdx_diff_check(
         [
             os.fspath(sbom_data_path.joinpath(sbom_ref).resolve(strict=True)),
             os.fspath(sbom_data_path.joinpath(sbom_new).resolve(strict=True)),
-            "--format",
-            "json",
-            "--output",
+            "--json-output",
             os.fspath(out_path),
             *extra_args,
         ],