Remove unused imports

android/src/main/java/com/RNFetchBlob/RNFetchBlobReq.java

 import java.net.SocketException;
 import java.net.SocketTimeoutException;
 import java.net.URL;
-import java.nio.ByteBuffer;
-import java.nio.charset.CharacterCodingException;
-import java.nio.charset.Charset;
-import java.nio.charset.CharsetEncoder;
 import java.security.KeyStore;
 import java.util.ArrayList;
 import java.util.Arrays;