fix missing import in 98629ef

Author: overheadhunter

src/main/java/org/cryptomator/cryptofs/fh/ChunkCache.java

@@ -10,6 +10,7 @@
 import java.io.IOException;
 import java.io.UncheckedIOException;
 import java.nio.ByteBuffer;
+import java.nio.channels.NonWritableChannelException;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.locks.ReadWriteLock;