Add support for newer androidx.preference library

Author: jobot0

build.gradle

@@ -56,6 +56,7 @@ ext{
             test: '1.1.0',
             legacySupport: '1.0.0',
             appcompat: '1.0.2',
+            preference: '1.0.0'
         ],
         testing: [
                 okhttp3: '3.11.0',

trustkit/build.gradle

@@ -28,6 +28,7 @@ repositories {
 dependencies {
     implementation "androidx.annotation:annotation:$rootProject.libVersions.androidx.annotation"
     implementation "androidx.legacy:legacy-support-v4:$rootProject.libVersions.androidx.legacySupport"
+    implementation "androidx.preference:preference:$rootProject.libVersions.androidx.preference"
 
     androidTestImplementation "junit:junit:$rootProject.libVersions.junit"
     androidTestImplementation "androidx.test:runner:$rootProject.libVersions.androidx.test"

trustkit/src/main/java/com/datatheorem/android/trustkit/utils/VendorIdentifier.java

@@ -3,8 +3,10 @@
 
 import android.content.Context;
 import android.content.SharedPreferences;
-import android.preference.PreferenceManager;
-import android.support.annotation.NonNull;
+
+import androidx.annotation.NonNull;
+import androidx.preference.PreferenceManager;
+
 import java.util.UUID;
 
 /**