fix wallet unit-tests

Signed-off-by: Angelo De Caro <adc@zurich.ibm.com>

Author: adecaro

token/services/identity/role/wallets_test.go

@@ -234,7 +234,7 @@ func TestLongTermOwnerWallet(t *testing.T) {
 		// Balance
 		bal, err := w.Balance(t.Context(), &driver.ListTokensOptions{Context: t.Context()})
 		require.NoError(t, err)
-		assert.Equal(t, uint64(30), bal)
+		assert.Equal(t, big.NewInt(30), bal)
 	})
 
 	t.Run("GetSigner", func(t *testing.T) {