Increase default process timeout

[clue]

Currently, we're not explicitly specifying a timeout to symfony's process manager when launching composer to install dependencies. As such, it assumes a default timeout of 60s.

Depending on the internet connection, using composer to install e.g. phpunit/phpunit takes too long and hence the process will be interrupted.

We should remove the timeout altogether.

Steps to reproduce:

$ phar-composer install phpunit/phpunit:3.7.*
[1/2] Installing phpunit/phpunit:3.7.* to temporary directory /tmp/phar-composer7 (using /usr/local/bin/composer create-project 'phpunit/phpunit:3.7.*' '/tmp/phar-composer7' --no-dev --no-progress --no-scripts)

    Installing phpunit/phpunit (3.7.32)
      - Installing phpunit/phpunit (3.7.32)
    Failed to download phpunit/phpunit from dist: You must enable the openssl extension to download files via https
    Now trying to download from source
      - Installing phpunit/phpunit (3.7.32)
        Cloning 2752cbb9ea5bd84c2811b34b6953f76965ec7a2f


  [Symfony\Component\Process\Exception\RuntimeException]  
  The process timed-out.                                  



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