Converting strings to numbers for comparison in lua script (#3847)

_Lua will automatically convert string and number types to the correct format to perform calculations. (...) A notable exception: comparison operators (== ~= < > <= >=) do not coerce their arguments._

Fixes: #3767

src/Microsoft.AspNet.SignalR.Redis/RedisConnection.cs

@@ -91,8 +91,8 @@ public async Task RestoreLatestValueForKey(int database, string key)
                 }
 
                 var redisResult = await _connection.GetDatabase(database).ScriptEvaluateAsync(
-                   @"local newvalue = redis.call('GET', KEYS[1])
-                     if not newvalue or newvalue < ARGV[1] then
+                   @"local newvalue = tonumber(redis.call('GET', KEYS[1]))
+                     if not newvalue or tonumber(newvalue) < tonumber(ARGV[1]) then
                          return redis.call('SET', KEYS[1], ARGV[1])
                      else
                          return nil