Unsupported special characters in password

**Expected result:** to be able to login with the credentials defined in with the browser interface.

**Actual result:** the android application tells me that it doesn't find matching credentials on the server.

Hi,
First and foremost thanks a lot for this really usefull app!
I love to be able to monitor my RaspberryPi health just by reading notifications on my phone.

It isn't a blocking issue but i thought that i would report it in order to prevent others to spend too much time on this.

Those are the steps to reproduce the issue:
- I have a gotify server with a publicly accessible interface and an administrator account.
- I changed the account password to this: 5aCx5€V)MDU{%AV0}v68 (nextcloud password generation)
- Logs in fine with the browser based interface but doesn't find a match with the android app.
- Switched to a alphanumeric only password and it works just fine everywhere.

**Here are the android logs:**
>> 2021-03-03T19:08:33.490Z ERROR: Error while api call
Code(401) Response: {"error":"Unauthorized","errorCode":401,"errorDescription":"you need to provide a valid access token or user credentials to access this api"}
at com.github.gotify.api.Callback$RetrofitCallback.onResponse(Callback.java:74)
at retrofit2.ExecutorCallAdapterFactory$ExecutorCallbackCall$1$1.run(ExecutorCallAdapterFactory.java:71)
at android.os.Handler.handleCallback(Handler.java:883)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:237)
at android.app.ActivityThread.main(ActivityThread.java:8167)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:496)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1100)

**Additional informations:**
I tested with the latest docker version and the app has been updated on 14 Feb 2021.