add git.iim.gay/grufwub/go-store for storage backend, replacing blob.Storage

Signed-off-by: kim (grufwub) <grufwub@gmail.com>

vendor/git.iim.gay/grufwub/go-errors/std.go

@@ -0,0 +1,18 @@
+package errors
+
+import "errors"
+
+// Is wraps "errors".Is()
+func Is(err, target error) bool {
+	return errors.Is(err, target)
+}
+
+// As wraps "errors".As()
+func As(err error, target interface{}) bool {
+	return errors.As(err, target)
+}
+
+// Unwrap wraps "errors".Unwrap()
+func Unwrap(err error) error {
+	return errors.Unwrap(err)
+}