如何要把xls文件转换成xlsx文件？

from docxtpl import DocxTemplate
from openpyxl import load_workbook
import os
def replace(obj):
    if obj is None:
        obj = ''
        return obj
# 加载要填入的数据
wb = load_workbook(r"D:\用户目录\Desktop\DCC运费\222.xlsx")
ws = wb['Sheet1']
contexts = []
for row in range(2, ws.max_row + 1):
    name = ws["D" + str(row)].value
    dcc = ws["O" + str(row)].value
    dcc = str(dcc).split('.')[0] + '.' + str(dcc).split('.')[1][:2]
    context = {"name": name, "dcc": dcc}
    contexts.append(context)
contexts
os.mkdir("./运费")
for context in contexts:
    print(context)
    tpl = DocxTemplate(r"D:\用户目录\Desktop\DCC运费\运费计算说明.docx")
    tpl.render(context)
    tpl.save("./运费/DCC运费{}.docx".format(context["name"]))

import pandas as pd
df = pd.read_excel('test9-11.xls', header=None)
df.to_excel('test9-11.xlsx', index=False, header=None)