title: issue with Userfrosting & Composer - no matching packages
body: <p>Just working my way through the Userfrosting 4 tutorial.  The basic app is up and running and am now creating the first sprinkle under "Your First UserFrosting Site".  </p>
  
  <p>On running composer update I get the following:</p>
  
  <pre><code>Loading composer repositories with package information
  </code></pre>
  
  <p>Updating dependencies (including require-dev)<br>
  Your requirements could not be resolved to an installable set of packages.</p>
  
  <pre><code> Problem 1
  - userfrosting/config dev-master requires userfrosting/support ^4.0.0 -&gt; no matching package found.
  - userfrosting/config dev-master requires userfrosting/support ^4.0.0 -&gt; no matching package found.
  - Installation request for userfrosting/config dev-master -&gt; satisfiable by userfrosting/config[dev-master].
  
  Potential causes:
   - A typo in the package name
   - The package is not available in a stable-enough version according to your minimum-stability setting
  </code></pre>
  
  <p>I've replaced my code with the copied / pasted code from the tutorial and still get the errors. I've absolutely no idea where to go from here - any pointers would be appreciated.</p>