Update Montreal community URL (#209)

We are migrating the community from Meetup to Guild Host—Meetup.com is becoming expensive and Guild Host seems a great alternative for us.

communities/montreal.json

@@ -1,6 +1,6 @@
 {
   "name": "Software Crafters Montreal",
-  "url": "https://www.meetup.com/Software-Crafters-Montreal/",
+  "url": "https://guild.host/software-crafters-montreal",
   "location": {
     "city": "Montreal, QC, Canada",
     "coordinates": { "lat": 45.52663715669149, "lng": -73.60701487863523 }