Update nitrokey crate to 0.4.0-alpha.2

This change updates the dependency to nitrokey to version 0.4.0-alpha.2.
In addition to minor interface changes for the get_*_firmware_version
and get_*_retry_count functions, several functions that change the
device state now require a mutable handle to the nitrokey. Hence, this
patch a number of function signatures to accept mutable device objects.

Import subrepo nitrokey/:nitrokey at 34efcfadf1436102e42144f710edabaa2c4b55cd

1 files changed, 7 insertions, 0 deletions

diff --git a/nitrokey/CHANGELOG.md b/nitrokey/CHANGELOG.md
index 24c79af..e98e857 100644
--- a/nitrokey/CHANGELOG.md
+++ b/nitrokey/CHANGELOG.md
@@ -31,6 +31,13 @@ SPDX-License-Identifier: MIT
   - Return `Error::Utf8Error` if libnitrokey returns an invalid UTF-8 string.
 - Implement `From<(T: Device, Error)>` for `Error`.
 - Fix timing issues with the `totp_no_pin` and `totp_pin` test cases.
+- Always return a `Result` in functions that communicate with a device.
+- Combine `get_{major,minor}_firmware_version` into `get_firmware_version`.
+- Add `set_encrypted_volume_mode` to `Storage`.
+- Use mutability to represent changes to the device status:
+  - Implement `DerefMut` for `User<T>` and `Admin<T>`.
+  - Add `device_mut` method to `DeviceWrapper`.
+  - Require a mutable `Device` reference if a method changes the device state.
 
 # v0.3.4 (2019-01-20)
 - Fix authentication methods that assumed that `char` is signed.