handle unlimited connections when terminating sessions. (#536)

internal/db/migrations/postgres/51_connection.up.sql

@@ -336,11 +336,15 @@ create or replace function
         now() > us.expiration_time or 
         -- connection limit reached...
         (
-          select count (*) 
-            from session_connection sc 
-          where 
-            sc.session_id = us.public_id
-        ) >= connection_limit or 
+          -- handle unlimited connections...
+          connection_limit != -1 and
+          (
+            select count (*) 
+              from session_connection sc 
+            where 
+              sc.session_id = us.public_id
+          ) >= connection_limit
+        ) or 
         -- canceled sessions
         us.public_id in (
           select