correct /etc/apt/sources.list for bullseye

I am getting errors about missing repository file on my 32-bit
bullseye installation on an old[ish] Raspberry Pi system.

So, when I run 'apt update' I see:-

    root@odinpi# apt update
    Hit:1 http://archive.raspberrypi.org/debian bullseye InRelease
    Hit:2 http://raspbian.raspberrypi.org/raspbian bullseye InRelease
    Ign:3 http://raspbian.raspberrypi.org/raspbian main InRelease
    Err:4 http://raspbian.raspberrypi.org/raspbian main Release
      404  Not Found [IP: 93.93.128.193 80]
    Get:5 https://apt.syncthing.net syncthing InRelease
    Reading package lists... Done
                              
    E: The repository 'http://raspbian.raspberrypi.org/raspbian main Release' does not have a Release file.
    N: Updating from such a repository can't be done securely, and is therefore disabled by default.
    N: See apt-secure(8) manpage for repository creation and user configuration details.

So, how do I get my /etc/apt/sources.list configured right?  I've not
manually edited it as far as I remember.

The file /etc/apt/sources.list is currently:-

    deb http://raspbian.raspberrypi.org/raspbian/ bullseye main contrib non-free rpi
    # Uncomment line below then 'apt-get update' to enable 'apt-get source'
    #deb-src http://raspbian.raspberrypi.org/raspbian/ bullseye main contrib non-free rpi
    deb http://raspbian.raspberrypi.org/raspbian/ main contrib non-free rpi

--
Chris Green
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