title: Poetry doesn't use the correct version of Python
body: <p>I've recently installed both Pyenv and Poetry and want to create a new Python 3.8 project. I've set both the <code>global</code> and <code>local</code> versions of python to <code>3.8.1</code> using the appropriate Pyenv commands (<code>pyenv global 3.8.1</code> for example). When I run <code>pyenv version</code> in my terminal the output is <code>3.8.1.</code> as expected.</p>
  
  <p>Now, the problem is that when I create a new python project with Poetry (<code>poetry new my-project</code>), the generated <code>pyproject.toml</code> file creates a project with python 2.7:</p>
  
  <pre><code>[tool.poetry]
  name = "my-project"
  version = "0.1.0"
  description = ""
  authors = ["user &lt;user@email.com&gt;"]
  
  [tool.poetry.dependencies]
  python = "^2.7"
  
  [tool.poetry.dev-dependencies]
  pytest = "^4.6"
  
  [build-system]
  requires = ["poetry&gt;=0.12"]
  build-backend = "poetry.masonry.api"
  </code></pre>
  
  <p>It seems that Poetry defaults back to the system version of Python. How do I change this so that it uses the version installed with Pyenv?</p>
  
  <p><strong>Edit</strong></p>
  
  <p>I'm using MacOS, which comes bundled with Python 2.7. I think that might be causing some of the issues here. I've reinstalled Python 3.8 again with Pyenv, but when I hit <code>Poetry install</code> I get the following error:</p>
  
  <pre><code>The currently activated Python version 2.7.16 is not supported by the project (^3.8).
  Trying to find and use a compatible version.
  
  [NoCompatiblePythonVersionFound]
  Poetry was unable to find a compatible version. If you have one, you can explicitly use it via the "env use" command. 
  </code></pre>
  
  <p>Should I create an environment explicitly for the project using Pyenv or should the project be able to access the correct Python version after running <code>pyenv local 3.8.1.</code>? When I do the latter, nothing changes and I still get the same errors.</p>