🔗 Update link for matrix and other to use https

Author: dpshelio

ch04packaging/01Libraries.ipynb

@@ -94,7 +94,7 @@
     "    * emails to developer list\n",
     "    * personal emails\n",
     "    * tweets\n",
-    "    * [irc](https://freenode.net)/[gitter](http://gitter.im/)/[slack](http://slack.com/)/[[matrix]](http://riot.im/)\n",
+    "    * [irc](https://freenode.net)/[gitter](https://gitter.im/)/[slack](https://slack.com/)/[[matrix]](https://element.io/)\n",
     "    * issues raised on GitHub\n",
     "* Are there contributors other than the lead contributor?\n",
     "* Is there discussion of the library on Stack Exchange?\n",