Update footer (#657)

* Add YouTube link to footer

* Remove link to Twitter from footer

* Add link to official LinkedIn to footer

Author: mpfaff

layouts/partials/footer.html

@@ -18,7 +18,12 @@
     <a href="https://www.facebook.com/CarletonComputerScienceSociety"
       ><i class="fab fa-facebook"></i
     ></a>
-    <a href="https://twitter.com/carletoncss"><i class="fab fa-twitter"></i></a>
+    <a href="https://ca.linkedin.com/company/carleton-computer-science-society"
+      ><i class="fab fa-linkedin"></i
+    ></a>
+    <a href="https://www.youtube.com/@carletoncomputersciencesoc305"
+      ><i class="fab fa-youtube"></i
+    ></a>
     <a href="https://github.com/CarletonComputerScienceSociety"
       ><i class="fab fa-github"></i
     ></a>