Put QR code in repo in case that GitHub availablility issue happens again

Author: stefmolin

images/qr-code.png

@@ -2110,7 +2110,7 @@ <h2>Thank you!</h2>
                   alt="Please visit https://stefaniemolin.com/feedback to provide your feedback on this session."
                   title="QR code to submit feedback (leads to https://stefaniemolin.com/feedback)"
                   class="qr-code"
-                  src="https://raw.githubusercontent.com/stefmolin/pandas-workshop/main/media/qr-code.png"
+                  src="images/qr-code.png"
                 />
               </a>
             </div>