message: Add: `purser-metamask` sign w/o address unit test
diff: @@ -256,6 +256,14 @@ describe('Metamask` Wallet Module', () => {
  firstArgument: mockedTransactionObject,
  });
  });
  + test('Sign a transaction without a destination address', async () => {
  + const metamaskWallet = new MetamaskWalletClass({ address });
  + expect(
  + metamaskWallet.sign({
  + value: 'mockedValue',
  + }),
  + ).resolves.not.toThrow();
  + });
  test('Calls the correct method to sign a message', async () => {
  const metamaskWallet = new MetamaskWalletClass({ address });
  await metamaskWallet.signMessage();
  