accounts/abi/bind: fix up Go mod files for Go 1.16

accounts/abi/bind/bind_test.go

@@ -1846,11 +1846,16 @@ func TestGolangBindings(t *testing.T) {
 		t.Fatalf("failed to convert binding test to modules: %v\n%s", err, out)
 	}
 	pwd, _ := os.Getwd()
-	replacer := exec.Command(gocmd, "mod", "edit", "-replace", "github.com/ethereum/go-ethereum="+filepath.Join(pwd, "..", "..", "..")) // Repo root
+	replacer := exec.Command(gocmd, "mod", "edit", "-x", "-require", "github.com/ethereum/go-ethereum@v0.0.0", "-replace", "github.com/ethereum/go-ethereum="+filepath.Join(pwd, "..", "..", "..")) // Repo root
 	replacer.Dir = pkg
 	if out, err := replacer.CombinedOutput(); err != nil {
 		t.Fatalf("failed to replace binding test dependency to current source tree: %v\n%s", err, out)
 	}
+	tidier := exec.Command(gocmd, "mod", "tidy")
+	tidier.Dir = pkg
+	if out, err := tidier.CombinedOutput(); err != nil {
+		t.Fatalf("failed to tidy Go module file: %v\n%s", err, out)
+	}
 	// Test the entire package and report any failures
 	cmd := exec.Command(gocmd, "test", "-v", "-count", "1")
 	cmd.Dir = pkg