rebase: bump github.com/aws/aws-sdk-go-v2/service/sts

Bumps [github.com/aws/aws-sdk-go-v2/service/sts](https://github.com/aws/aws-sdk-go-v2) from 1.16.7 to 1.16.9.
- [Release notes](https://github.com/aws/aws-sdk-go-v2/releases)
- [Changelog](https://github.com/aws/aws-sdk-go-v2/blob/main/CHANGELOG.md)
- [Commits](https://github.com/aws/aws-sdk-go-v2/compare/v1.16.7...service/ivs/v1.16.9)

---
updated-dependencies:
- dependency-name: github.com/aws/aws-sdk-go-v2/service/sts
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

vendor/github.com/aws/smithy-go/CHANGELOG.md

@@ -1,3 +1,9 @@
+# Release (v1.12.0)
+
+## Module Highlights
+* `github.com/aws/smithy-go`: v1.12.0
+  * **Feature**: `transport/http`: Add utility for setting context metadata when operation serializer automatically assigns content-type default value.
+
 # Release (v1.11.3)
 
 ## Module Highlights

vendor/github.com/aws/smithy-go/go_module_metadata.go

@@ -3,4 +3,4 @@
 package smithy
 
 // goModuleVersion is the tagged release for this module
-const goModuleVersion = "1.11.3"
+const goModuleVersion = "1.12.0"

vendor/github.com/aws/smithy-go/transport/http/middleware_headers.go

@@ -7,6 +7,85 @@ import (
 	"github.com/aws/smithy-go/middleware"
 )
 
+type isContentTypeAutoSet struct{}
+
+// SetIsContentTypeDefaultValue returns a Context specifying if the request's
+// content-type header was set to a default value.
+func SetIsContentTypeDefaultValue(ctx context.Context, isDefault bool) context.Context {
+	return context.WithValue(ctx, isContentTypeAutoSet{}, isDefault)
+}
+
+// GetIsContentTypeDefaultValue returns if the content-type HTTP header on the
+// request is a default value that was auto assigned by an operation
+// serializer. Allows middleware post serialization to know if the content-type
+// was auto set to a default value or not.
+//
+// Also returns false if the Context value was never updated to include if
+// content-type was set to a default value.
+func GetIsContentTypeDefaultValue(ctx context.Context) bool {
+	v, _ := ctx.Value(isContentTypeAutoSet{}).(bool)
+	return v
+}
+
+// AddNoPayloadDefaultContentTypeRemover Adds the DefaultContentTypeRemover
+// middleware to the stack after the operation serializer. This middleware will
+// remove the content-type header from the request if it was set as a default
+// value, and no request payload is present.
+//
+// Returns error if unable to add the middleware.
+func AddNoPayloadDefaultContentTypeRemover(stack *middleware.Stack) (err error) {
+	err = stack.Serialize.Insert(removeDefaultContentType{},
+		"OperationSerializer", middleware.After)
+	if err != nil {
+		return fmt.Errorf("failed to add %s serialize middleware, %w",
+			removeDefaultContentType{}.ID(), err)
+	}
+
+	return nil
+}
+
+// RemoveNoPayloadDefaultContentTypeRemover removes the
+// DefaultContentTypeRemover middleware from the stack. Returns an error if
+// unable to remove the middleware.
+func RemoveNoPayloadDefaultContentTypeRemover(stack *middleware.Stack) (err error) {
+	_, err = stack.Serialize.Remove(removeDefaultContentType{}.ID())
+	if err != nil {
+		return fmt.Errorf("failed to remove %s serialize middleware, %w",
+			removeDefaultContentType{}.ID(), err)
+
+	}
+	return nil
+}
+
+// removeDefaultContentType provides after serialization middleware that will
+// remove the content-type header from an HTTP request if the header was set as
+// a default value by the operation serializer, and there is no request payload.
+type removeDefaultContentType struct{}
+
+// ID returns the middleware ID
+func (removeDefaultContentType) ID() string { return "RemoveDefaultContentType" }
+
+// HandleSerialize implements the serialization middleware.
+func (removeDefaultContentType) HandleSerialize(
+	ctx context.Context, input middleware.SerializeInput, next middleware.SerializeHandler,
+) (
+	out middleware.SerializeOutput, meta middleware.Metadata, err error,
+) {
+	req, ok := input.Request.(*Request)
+	if !ok {
+		return out, meta, fmt.Errorf(
+			"unexpected request type %T for removeDefaultContentType middleware",
+			input.Request)
+	}
+
+	if GetIsContentTypeDefaultValue(ctx) && req.GetStream() == nil {
+		req.Header.Del("Content-Type")
+		input.Request = req
+	}
+
+	return next.HandleSerialize(ctx, input)
+}
+
 type headerValue struct {
 	header string
 	value  string