fix: shift_dst ON the DST hour

[Matsa59]

We encounter the same bug as explains in #304

The problem is caused because the validation rule system call multiple times the shift_dst function. So it applied multiple time the shift.

A simple solution is to check if the shift date have the same hour (in that case, we may want to apply dst)

--

btw sorry I had to update excoverall dunno why got ssl error on my mac
and also bus error on otp 25 so I just bump it to otp 26 (we use it in production at Omerlo for a while so IMO it's safe)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.60%. Comparing base (80b7c93) to head (a11b337).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #306   +/-   ##
=======================================
  Coverage   96.59%   96.60%           
=======================================
  Files          21       21           
  Lines         499      500    +1     
=======================================
+ Hits          482      483    +1     
  Misses         17       17           

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[Matsa59]

hum it may have a counter part : if the schedule rule is next hour it may not work.
But I guess it's better than an infinite loop

[Matsa59]

Ok there is a problem on day change (e.g. DST on midnight will change date to day - 1)
I'll work on that today

[Matsa59]

So here the bad news: the base system should use date instead of datetime :/