unjetify for private usage

android/src/main/java/fr/greweb/reactnativeviewshot/DebugViews.java

 import android.content.res.Resources;
 import android.graphics.Matrix;
 import android.os.Build;
-import androidx.annotation.NonNull;
-import androidx.core.util.Pair;
+import android.support.annotation.NonNull;
+import android.support.v4.util.Pair;
 import android.util.Log;
 import android.view.View;
 import android.view.ViewGroup;

android/src/main/java/fr/greweb/reactnativeviewshot/RNViewShotModule.java

 import android.content.Context;
 import android.net.Uri;
 import android.os.AsyncTask;
-import androidx.annotation.NonNull;
+import android.support.annotation.NonNull;
 import android.util.DisplayMetrics;
 import android.util.Log;
 

android/src/main/java/fr/greweb/reactnativeviewshot/ViewShot.java

 import android.graphics.Paint;
 import android.graphics.Point;
 import android.net.Uri;
-import androidx.annotation.IntDef;
-import androidx.annotation.NonNull;
-import androidx.annotation.StringDef;
+import android.support.annotation.IntDef;
+import android.support.annotation.NonNull;
+import android.support.annotation.StringDef;
 import android.util.Base64;
 import android.util.Log;
 import android.view.TextureView;