rpc: personal_unpair (#733)

* Problem: need to add rpc endpoint personal_unpair

Closes #730

* this is aimed at smartcard wallet which is not supported yet.

* will return unsupported error now.

* Update rpc/ethereum/namespaces/personal/api.go

* add changelog entry and use errors.Is

Co-authored-by: Federico Kunze Küllmer <31522760+fedekunze@users.noreply.github.com>
Co-authored-by: Tomas Tauber <2410580+tomtau@users.noreply.github.com>

tests/rpc/personal_test.go

@@ -2,6 +2,8 @@ package rpc
 
 import (
 	"encoding/json"
+	"errors"
+	"fmt"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -142,3 +144,13 @@ func TestPersonal_LockAccount(t *testing.T) {
 	_, err = CallWithError("personal_sign", []interface{}{hexutil.Bytes{0x88}, addr, ""})
 	require.Error(t, err)
 }
+
+func TestPersonal_Unpair(t *testing.T) {
+	t.Skip("skipping TestPersonal_Unpair")
+
+	rpcRes := Call(t, "personal_unpair", []interface{}{"", 0})
+
+	var res error
+	err := json.Unmarshal(rpcRes.Result, &res)
+	require.True(t, errors.Is(err, fmt.Errorf("smartcard wallet not supported yet")))
+}