fix: add support for Dart SDK package dependencies (#1891)

Signed-off-by: Stephane Rufer <1128559+rufman@users.noreply.github.com>

syft/pkg/cataloger/dart/parse_pubspec_lock.go

@@ -5,7 +5,7 @@ import (
 	"net/url"
 	"sort"
 
-	"gopkg.in/yaml.v2"
+	"gopkg.in/yaml.v3"
 
 	"github.com/anchore/syft/internal/log"
 	"github.com/anchore/syft/syft/artifact"
@@ -38,6 +38,23 @@ type pubspecLockDescription struct {
 	ResolvedRef string `yaml:"resolved-ref" mapstructure:"resolved-ref"`
 }
 
+func (p *pubspecLockDescription) UnmarshalYAML(value *yaml.Node) error {
+	type pld pubspecLockDescription
+	var p2 pld
+
+	if value.Decode(&p.Name) == nil {
+		return nil
+	}
+
+	if err := value.Decode(&p2); err != nil {
+		return err
+	}
+
+	*p = pubspecLockDescription(p2)
+
+	return nil
+}
+
 func parsePubspecLock(_ file.Resolver, _ *generic.Environment, reader file.LocationReadCloser) ([]pkg.Package, []artifact.Relationship, error) {
 	var pkgs []pkg.Package
 

syft/pkg/cataloger/dart/parse_pubspec_lock_test.go

@@ -79,6 +79,19 @@ func TestParsePubspecLock(t *testing.T) {
 				Version: "1.6.0",
 			},
 		},
+		{
+			Name:         "flutter",
+			Version:      "0.0.0",
+			PURL:         "pkg:pub/flutter@0.0.0",
+			Locations:    fixtureLocationSet,
+			Language:     pkg.Dart,
+			Type:         pkg.DartPubPkg,
+			MetadataType: pkg.DartPubMetadataType,
+			Metadata: pkg.DartPubMetadata{
+				Name:    "flutter",
+				Version: "0.0.0",
+			},
+		},
 		{
 			Name:         "key_binder",
 			Version:      "1.11.20",

syft/pkg/cataloger/dart/test-fixtures/pubspec.lock

@@ -36,6 +36,11 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.6.0"
+  flutter:
+    dependency: "direct main"
+    description: flutter
+    source: sdk
+    version: "0.0.0"
   key_binder:
     dependency: "direct main"
     description: