fix(codegen): remove unused import

Author: trivikr

codegen/smithy-aws-typescript-codegen/src/main/java/software/amazon/smithy/aws/typescript/codegen/AddHttpChecksumDependency.java

@@ -25,7 +25,6 @@
 import java.util.TreeMap;
 import java.util.function.Consumer;
 import software.amazon.smithy.aws.traits.HttpChecksumTrait;
-import software.amazon.smithy.codegen.core.Symbol;
 import software.amazon.smithy.codegen.core.SymbolProvider;
 import software.amazon.smithy.model.Model;
 import software.amazon.smithy.model.knowledge.TopDownIndex;