Add support for Singapore (#2)

Co-authored-by: sevensxyt <sevendotxyt@proton.me>
Reviewed-on: https://github.com/kennethnym/7am/pull/2

main.go

@@ -122,6 +122,7 @@ var supportedLocations = map[string]*location{
 	"la":        {nil, 34.052235, -118.243683, "America/Los_Angeles", "Los Angeles"},
 	"nyc":       {nil, 40.712776, -74.005974, "America/New_York", "New York City"},
 	"tokyo":     {nil, 35.689487, 139.691711, "Asia/Tokyo", "Tokyo"},
+	"singapore": {nil, 1.290270, 103.851959, "Asia/Singapore", "Singapore"},
 	"warsaw":    {nil, 52.229675, 21.012230, "Europe/Warsaw", "Warsaw"},
 	"zurich":    {nil, 47.369019, 8.538030, "Europe/Zurich", "Zurich"},
 	"berlin":    {nil, 52.520008, 13.404954, "Europe/Berlin", "Berlin"},

web/index.html

@@ -53,6 +53,7 @@
                 <li><a href="/warsaw">Warsaw</a></li>
                 <li><a href="/dubai">Dubai</a></li>
                 <li><a href="/tokyo">Tokyo</a></li>
+                <li><a href="/singapore">Singapore</a></li>
             </ul>
         </main>