title: Composer can't install Twig Extensions
body: <p>I tried installing the <code>twig/extensions</code> package in it's <code>dev-master</code> version in my Symfony 5 application. I am meeting the following output :</p>
  
  <pre><code>Your requirements could not be resolved to an installable set of packages.
  
    Problem 1
      - Installation request for twig/extensions dev-master -&gt; satisfiable by twig/extensions[dev-master].
      - Conclusion: remove twig/twig v3.0.3
      - Conclusion: don't install twig/twig v3.0.3
      - twig/extensions dev-master requires twig/twig ^2.10 -&gt; satisfiable by twig/twig[v2.10.0, v2.11.0, v2.11.1, v2.11.2, v2.11.3, v2.12.0, v2.12.1, v2.12.2, v2.12.3, v2.12.4, v2.12.5].
      - Can only install one of: twig/twig[v2.10.0, v3.0.3].
      - Can only install one of: twig/twig[v2.11.0, v3.0.3].
      - Can only install one of: twig/twig[v2.11.1, v3.0.3].
      - Can only install one of: twig/twig[v2.11.2, v3.0.3].
      - Can only install one of: twig/twig[v2.11.3, v3.0.3].
      - Can only install one of: twig/twig[v2.12.0, v3.0.3].
      - Can only install one of: twig/twig[v2.12.1, v3.0.3].
      - Can only install one of: twig/twig[v2.12.2, v3.0.3].
      - Can only install one of: twig/twig[v2.12.3, v3.0.3].
      - Can only install one of: twig/twig[v2.12.4, v3.0.3].
      - Can only install one of: twig/twig[v2.12.5, v3.0.3].
      - Installation request for twig/twig (locked at v3.0.3) -&gt; satisfiable by twig/twig[v3.0.3].
  </code></pre>
  
  <p>As the <a href="https://packagist.org/packages/twig/extensions#dev-master" rel="nofollow noreferrer">package page</a> seems to require <code>twig/twig</code> in its version <code>^2.10</code> I tried to find it there was a package requiring something conflictual in my project (for instance <code>^3.0</code>) but there do not seems to exist one :</p>
  
  <pre><code>$ composer why twig/twig
  knplabs/knp-paginator-bundle  v5.1.1  requires  twig/twig (^2.0 || ^3.0)
  symfony/twig-bridge           v5.0.4  requires  twig/twig (^2.10|^3.0)
  symfony/twig-bundle           v5.0.4  requires  twig/twig (^2.10|^3.0)
  symfony/twig-pack             v1.0.0  requires  twig/twig (^2.12|^3.0)
  symfony/web-profiler-bundle   v5.0.4  requires  twig/twig (^2.10|^3.0)
  twig/extra-bundle             v3.0.3  requires  twig/twig (^2.4|^3.0)
  </code></pre>
  
  <p>Could someone enlighten me on why Composer can't resolve my requirements ? Don't hesitate to ask for the output of more comments. I'll edit this accordingly.</p>
  
  <p>Here the <code>require</code> and <code>require-dev</code> keys of my <code>composer.json</code> :</p>
  
  <pre><code>"require": {
      "php": "^7.2.5",
      "ext-ctype": "*",
      "ext-iconv": "*",
      "antishov/doctrine-extensions-bundle": "^1.4",
      "knplabs/knp-paginator-bundle": "^5.1",
      "sensio/framework-extra-bundle": "^5.1",
      "symfony/asset": "5.0.*",
      "symfony/console": "5.0.*",
      "symfony/dotenv": "5.0.*",
      "symfony/expression-language": "5.0.*",
      "symfony/flex": "^1.3.1",
      "symfony/form": "5.0.*",
      "symfony/framework-bundle": "5.0.*",
      "symfony/http-client": "5.0.*",
      "symfony/intl": "5.0.*",
      "symfony/mailer": "5.0.*",
      "symfony/monolog-bundle": "^3.1",
      "symfony/notifier": "5.0.*",
      "symfony/orm-pack": "*",
      "symfony/process": "5.0.*",
      "symfony/security-bundle": "5.0.*",
      "symfony/serializer-pack": "*",
      "symfony/string": "5.0.*",
      "symfony/translation": "5.0.*",
      "symfony/twig-pack": "*",
      "symfony/validator": "5.0.*",
      "symfony/web-link": "5.0.*",
      "symfony/webpack-encore-bundle": "^1.7",
      "symfony/yaml": "5.0.*"
  },
  "require-dev": {
      "doctrine/doctrine-fixtures-bundle": "^3.3",
      "fzaninotto/faker": "^1.9",
      "symfony/debug-pack": "*",
      "symfony/maker-bundle": "^1.0",
      "symfony/profiler-pack": "*",
      "symfony/test-pack": "*"
  }
  </code></pre>