fix style

Author: timfel

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/CodecsModuleBuiltins.java

@@ -50,9 +50,7 @@
 import java.nio.charset.CharacterCodingException;
 import java.nio.charset.Charset;
 import java.nio.charset.CodingErrorAction;
-import java.nio.charset.IllegalCharsetNameException;
 import java.nio.charset.StandardCharsets;
-import java.nio.charset.UnsupportedCharsetException;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;