fix: separate golang license caches from mod dir (#2852)

Signed-off-by: Keith Zantow <kzantow@gmail.com>

internal/cache/memory_test.go

@@ -0,0 +1,37 @@
+package cache
+
+import (
+	"io"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/anchore/syft/internal"
+)
+
+func Test_NewInMemory(t *testing.T) {
+	man := NewInMemory(time.Hour)
+
+	cacheName := "test"
+	cacheVersion := "v1"
+	cache := man.GetCache(cacheName, cacheVersion)
+
+	cacheKey := "test-key"
+	contentsValue := "some contents to cache"
+
+	err := cache.Write(cacheKey, strings.NewReader(contentsValue))
+	require.NoError(t, err)
+
+	rdr, err := cache.Read(cacheKey)
+	require.NoError(t, err)
+	defer internal.CloseAndLogError(rdr, cacheKey)
+
+	contents, err := io.ReadAll(rdr)
+	require.NoError(t, err)
+	require.Equal(t, contentsValue, string(contents))
+
+	_, err = cache.Read("otherKey")
+	require.ErrorIs(t, err, errNotFound)
+}