chore: execute goimports to format the code (#7983)

* chore: execute goimports to format the code

Signed-off-by: promalert <promalert@outlook.com>

* goimports -w .

---------

Signed-off-by: promalert <promalert@outlook.com>
Co-authored-by: Chris Lu <chris.lu@gmail.com>

weed/s3api/policy/post-policy.go

@@ -20,10 +20,11 @@ package policy
 import (
 	"encoding/base64"
 	"fmt"
-	"github.com/seaweedfs/seaweedfs/weed/s3api/s3err"
 	"net/http"
 	"strings"
 	"time"
+
+	"github.com/seaweedfs/seaweedfs/weed/s3api/s3err"
 )
 
 // expirationDateFormat date format for expiration key in json policy.