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

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

internal/cache/bypass.go

@@ -0,0 +1,24 @@
+package cache
+
+import "io"
+
+type bypassedCache struct{}
+
+func (b *bypassedCache) Read(_ string) (ReaderAtCloser, error) {
+	return nil, errNotFound
+}
+
+func (b *bypassedCache) Write(_ string, contents io.Reader) error {
+	if closer, ok := contents.(io.Closer); ok {
+		_ = closer.Close()
+	}
+	return nil
+}
+
+func (b *bypassedCache) GetCache(_, _ string) Cache {
+	return b
+}
+
+func (b *bypassedCache) RootDirs() []string {
+	return nil
+}