Joffrey JAFFEUX 8edd2b38cb
FIX: ensures timeline_lookup includes last tuple (#11829)
A simplified version of the logic used in the function before my fix is as follow:

```ruby
result = []
things = [0,1,2,3]
max_values = 2
every = (things.size.to_f / max_values).ceil

things.each_with_index do |t, index|
  next unless (t % every) === 0
  result << t
end

p result # [0, 2]
# 3 doesn’t get included
```

The problem is that if you get unlucky two times you won't get last tuple(s) and might get a very erroneous date.

Double unlucky:
- last tuple index % computed every !== 0 and you don't get the last tuple
- the last tuple is related to a post with a very different date than the previous tuples (on year difference in our case)
2021-01-25 11:30:59 +01:00
..