fix: KotlinNullnessAnnotation warning (#829)

## 📜 Description

remove unnecessary @nullable Annotation in kotlin
```log
Error: Do not use @nullable in Kotlin; the nullability is already implied by the Kotlin type NativeModule? ending with ? [KotlinNullnessAnnotation]
  @nullable
  ~~~~~~~~~

   Explanation for issues of type "KotlinNullnessAnnotation":
   In Kotlin, nullness is part of the type system; s: String is never null and
   s: String? is sometimes null, whether or not you add in additional
   annotations stating @nonnull or @nullable. These are likely copy/paste
   mistakes, and are misleading.
```

## 💡 Motivation and Context

This problem will cause warning. Because warning as error, it will cause
build failed

## 📢 Changelog

### Android
remove unnecessary @nullable annotation
KeyboardControllerPackage.getModule

## 🤔 How Has This Been Tested?

This commit not include any code logic change, so this is unlikely to be
a problem.

## 📝 Checklist

- [x] CI successfully passed
- [x] I added new mocks and corresponding unit-tests if library API was
changed

Author: CubeSugarCheese

android/src/turbo/java/com/reactnativekeyboardcontroller/KeyboardControllerPackage.kt

@@ -1,6 +1,5 @@
 package com.reactnativekeyboardcontroller
 
-import androidx.annotation.Nullable
 import com.facebook.react.TurboReactPackage
 import com.facebook.react.bridge.NativeModule
 import com.facebook.react.bridge.ReactApplicationContext
@@ -11,7 +10,6 @@ import com.reactnativekeyboardcontroller.modules.KeyboardControllerModuleImpl
 import com.reactnativekeyboardcontroller.modules.StatusBarManagerCompatModuleImpl
 
 class KeyboardControllerPackage : TurboReactPackage() {
-  @Nullable
   override fun getModule(
     name: String,
     reactContext: ReactApplicationContext,