如何在Lando上安装pecl_http(HttpRequest)?

I'm working on a PHP-project and there is a 3rd party API-wrapper that uses HttpRequest class (so it requires PECL_HTTP PHP-library to be installed). I'm using Lando (v3.0.0-rc.12) for local development with the basic LAMP reciepe:

recipe: lamp
config:
  webroot: .
  php: '5.6'

And with this set up I got a Fatal error: Class 'HttpRequest' not found when I try to call the class like this $request = new HttpRequest( $url );.

Based on discussions here, here and there I've tried to install PECL_HTTP on Lando by adding the following configuration to my lando.yml file:

services:
  appserver:
    build_as_root:
     - apt-get update -y
     - apt-get install -y curl libcurl3 libcurl4-gnutls-dev libmagic-dev
     - pecl install -f pecl_http-1.7.6
     - docker-php-ext-enable pecl_http

This does not help and HttpRequest is still unavailable, while lando start shows this error message on installation of the packages:

 Starting projectname_appserver_1 ... done
 Get:1 http://security.debian.org jessie/updates InRelease [44.9 kB]
 Ign http://deb.debian.org jessie InRelease
 Get:2 http://deb.debian.org jessie-updates InRelease [7340 B]
 Get:3 http://deb.debian.org jessie Release.gpg [2420 B]
 Get:4 http://deb.debian.org jessie Release [148 kB]
 Get:5 http://security.debian.org jessie/updates/main amd64 Packages [831 kB]
 Get:6 http://deb.debian.org jessie/main amd64 Packages [9098 kB]
 Fetched 10.1 MB in 10s (980 kB/s)
 W: Failed to fetch http://deb.debian.org/debian/dists/jessie-updates/InRelease  Unable to find expected entry 'main/binary-amd64/Packages' in  Release file (Wrong sources.list entry or malformed file)
 E: Some index files failed to download. They have been ignored, or old ones used instead.

And I'm running out of ideas. What am I doing wrong?