fix: handle empty day in time program

[codecov-commenter]

Codecov Report

All modified lines are covered by tests :white_check_mark:

Comparison is base (5ce17ba) 98.45% compared to head (2c132bf) 98.45%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #117 +/- ## ======================================= Coverage 98.45% 98.45% ======================================= Files 27 27 Lines 1942 1943 +1 ======================================= + Hits 1912 1913 +1 Misses 30 30 ``` | [Files](https://app.codecov.io/gh/thomasgermain/pymultiMATIC/pull/117?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Thomas+Germain) | Coverage Δ | | |---|---|---| | [pymultimatic/model/mapper.py](https://app.codecov.io/gh/thomasgermain/pymultiMATIC/pull/117?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Thomas+Germain#diff-cHltdWx0aW1hdGljL21vZGVsL21hcHBlci5weQ==) | `96.63% <100.00%> (+<0.01%)` | :arrow_up: |

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