Metobs integration test hard-codes date

[docNord]

In the Metobs integration test, the date range is explicitly hard-coded when downloading data from Karesuando (the header when reading corrected-archive, which is compared using string comparison, is changed in the data file monthly), causing a monthly recurring bug.

@mgcth can you have a look at this?

[mgcth]

Great that you found it!

[mgcth]

Writing here for documentation, but see #43, too.

@docNord, for tests to pass, we could have a {{ date }} key in the head string and do

head = head.replace("{{ date }}", datetime.date.today().strftime("%Y-%m") + "-01")