Update README.md

Author: itsubaki

README.md

@@ -2,7 +2,7 @@
 
 [![PkgGoDev](https://pkg.go.dev/badge/github.com/itsubaki/neu)](https://pkg.go.dev/github.com/itsubaki/neu)
 [![Go Report Card](https://goreportcard.com/badge/github.com/itsubaki/neu?style=flat-square)](https://goreportcard.com/report/github.com/itsubaki/neu)
-[![tests](https://github.com/itsubaki/neu/workflows/tests/badge.svg?branch=main)](https://github.com/itsubaki/neu/actions)
+[![tests](https://github.com/itsubaki/neu/workflows/tests/badge.svg)](https://github.com/itsubaki/neu/actions)
 [![codecov](https://codecov.io/gh/itsubaki/neu/branch/main/graph/badge.svg?token=KMJ2GUC1FJ)](https://codecov.io/gh/itsubaki/neu)
 
 - Deep Learning framework for Go from scratch