403 Forbidden - lighttpd

Question

I have a raspberry pi with Raspbian Version Linux RaspberryPi 4.19.97-v7+ #1294 SMP Thu Jan 30 13:15:58 GMT 2020 armv7l GNU/Linux and a lighttpd webserver installed.

$ sudo mkdir /var/www 
$ sudo groupadd www-data 
$ sudo adduser www-data www-data 
$ sudo usermod -a -G www-data www-data 
$ sudo chown -R www-data:www-data /var/www 
$ sudo apt-get update 
$ sudo apt-get install lighttpd
$ sudo apt-get install php7.3-fpm php7.3 
$ sudo lighty-enable-mod fastcgi 
$ sudo lighty-enable-mod fastcgi-php

I edit the configuration of /etc/lighttpd/conf-available/15-fastcgi-php.conf

fastcgi.server = ( ".php" => 
    ((
        "bin-path" => "/usr/bin/php-cgi7.3",  
        "socket" => "/var/run/php/php7.3-fpm.sock",
        "broken-scriptfilename" => "enable"
    ))
)

And my lighttpd.conf

server.modules = (
    "mod_access",
    "mod_alias",
    "mod_compress",
    "mod_redirect",
    "mod_fastcgi",
)

server.document-root    = "/var/www"
server.upload-dirs      = ("/var/cache/lighttpd/uploads")
server.error-log        = "/var/log/lighttpd/error.log"
server.pid-file         = "/var/run/lighttpd.pid"
server.username         = "www-data"
server.groupname        = "www-data"
server.port             = 80
server.indexfiles       = ("index.php", "index.html")

mimetype.assign   = ( ".png"  => "image/png",
                      ".jpg"  => "image/jpeg",
                      ".jpeg" => "image/jpeg",
                      ".html" => "text/html",
                      ".txt"  => "text/plain"
)

static-file.exclude-extensions = (".php", ".pl", ".fcgi")

dir-listing.encoding    = "utf-8"
server.dir-listing      = "enable"

$HTTP["url"] =~ "^/($|/)" { 
dir-listing.activate = "disable"
}

And also /etc/php/7.3/fpm/php.ini

cgi.fix_pathinfo=1

I reboot the Raspberry Pi and get the error 403 when I want to access my phpinfo() website.

The permissions for the directory /var/www are the following:

$ ls -l /var/www

-rwxr-xr-x 1 www-data www-data 2751 Mär 22 15:29 GPIO.html
drwxr-xr-x 2 root     root     4096 Mär 22 21:26 html
-rwxr-xr-x 1 www-data www-data   24 Mär 22 15:15 index.php

The PHP file is located under /var/www.

So what is wrong?