I have this Dockerfile:

FROM php:8.1.0-fpm

RUN apt-get update 
    && apt-get install -y zlib1g-dev g++ git libicu-dev zip libzip-dev zip libpng-dev libssl-dev libxslt-dev wkhtmltopdf procps acl 
    && pecl install apcu 
    && docker-php-ext-install intl opcache pdo pdo_mysql zip gd xsl -j$(nproc) 
    && docker-php-ext-enable apcu opcache 
    && docker-php-ext-configure zip

# xmlrpc
# channel://pecl.php.net/xmlrpc-1.0.0RC3
# php-xmlrpc
# php-xml-rpc
# php8.1-xmlrpc
# php-pecl-xmlrpc
# php81-pecl-xmlrpc
# xmlrpc-1.0.0RC3

I've tried a lot of ways to include XML-RPC in it (see the commented line), but nothing works. I know this package is deprecated, but it's a dependency I absolutely need. It works fine in PHP 7.4, but I can't figure out what's going on with PHP 8.1.

Can anyone tell me?