Removing unused imports.

Author: ppisl

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/str/StringBuiltins.java

@@ -107,7 +107,6 @@
 import com.oracle.truffle.api.dsl.TypeSystemReference;
 import com.oracle.truffle.api.profiles.BranchProfile;
 import com.oracle.truffle.api.profiles.ConditionProfile;
-import java.nio.charset.StandardCharsets;
 
 @CoreFunctions(extendClasses = PythonBuiltinClassType.PString)
 public final class StringBuiltins extends PythonBuiltins {