message: Fix tests descriptions for hex keys test
diff: @@ -77,7 +77,7 @@ struct HexKeys : public AcceptanceFixture {
  /**
  * @given an account with kAddSignatory permission
  - * @when an the same public key is used twice but written in different case
  + * @when the same public key is used twice but written in different case
  * @then only first attempt to add the key succeeds
  */
  TEST_F(HexKeys, AddSignatory) {
  @@ -104,7 +104,7 @@ TEST_F(HexKeys, AddSignatory) {
  * first.
  *
  * @given an account with kAddSignatory permission
  - * @when an the same public key is used twice but written in different case
  + * @when the same public key is used twice but written in different case
  * @then only first attempt to add the key succeeds
  */
  TEST_F(HexKeys, AddSignatoryReverse) {
  