[FIX} - github lego breaking when data includes two diferent years

[stefi-says]

today the app accepts the date the user wants the behaviour to be checked upon and checks 6 months back on time, but if the date inputed minus 6 months enduo on a diferent year, the lego breaks given the 'tretened_df()' module way of filtering the data

[stefi-says]

Inside de function " tretened_df" of the github lego there are functions to calculate the date the user input - 6 months. When this calculation results in a date that is not in the same year of the inputed date the final treatened df return a dataframe where the columns are not following the correct order of the dates ( sundays ) or it skips weeks. @G-r-ay