Add dart support (#919)

Co-authored-by: Alex Goodman <alex.goodman@anchore.com>

syft/pkg/language_test.go

@@ -1,9 +1,10 @@
 package pkg
 
 import (
+	"testing"
+
 	"github.com/scylladb/go-set/strset"
 	"github.com/stretchr/testify/assert"
-	"testing"
 )
 
 func TestLanguageFromPURL(t *testing.T) {
@@ -29,6 +30,10 @@ func TestLanguageFromPURL(t *testing.T) {
 			purl: "pkg:golang/github.com/gorilla/context@234fd47e07d1004f0aed9c",
 			want: Go,
 		},
+		{
+			purl: "pkg:pub/util@1.2.34",
+			want: Dart,
+		},
 		{
 			purl: "pkg:cargo/clap@2.33.0",
 			want: Rust,