update sponsors (Codeception#455)

Author: Arhell

_includes/sponsors.html

@@ -2,6 +2,15 @@
   <div class="container">
     <div class="row">
       <div class="col-sm-12 col-md-offset-3 col-md-6 text-center">
+        <a href="https://opencollective.com/codeception/contribute/premium-partner-11916/checkout">
+          <h3>Premium Sponsors</h3>
+        </a>
+
+
+        <a href="https://somewherewarm.com/" rel="nofollow" class="sponsors-item">
+          <img src="https://images.opencollective.com/somewherewarmgr/f8b567b/logo/256.png" alt="SomewhereWarm" title="SomewhereWarm - Living and breathing all things WooCommerce. " class="sponsors sponsors--somewherewarm">
+        </a>
+
         <a href="https://opencollective.com/codeception/contribute/sponsor-11887/checkout">
           <h4>Sponsors</h4>
         </a>