安装php7.4，发现之前用的php-xdebug和php-redis都没了。

想安装旧版本的php7.3，然后直接apt仓库里面没有。

根据网上搜索的先添加仓库 sudo add-apt-repository ppa:ondrej/php，又提示以下错误

Traceback (most recent call last):
  File "/usr/bin/add-apt-repository", line 95, in 
    sp = SoftwareProperties(options=options)
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", line 109, in __init__
    self.reload_sourceslist()
  File "/usr/lib/python3/dist-packages/softwareproperties/SoftwareProperties.py", line 599, in reload_sourceslist
    self.distro.get_sources(self.sourceslist)  
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/aptsources/distro.py", line 89, in get_sources
    raise NoDistroTemplateException(
aptsources.distro.NoDistroTemplateException: Error: could not find a distribution template for Deepin/beige