fix off-by-one bug for hamster export tsv

[GeraldJansen]

This PR is a workaround for a bug concerning the range.end in some date ranges (#576).

A better fix would address the issue in hamster.lib.datetime.Range.from_start_end(), but my attempts there created other problems.

[GeraldJansen]

@elbenfreund Hmm, I signed the CLA long ago. Now if I click on the CLA banner I get this message:

Error
There is no CLA to sign for projecthamster/hamster
(could not find linked item for owner projecthamster and repo hamster)

[elbenfreund]

My appologies @GeraldJansen as explained here I triggered a project wide refresh when I started working on hamster-*. I disabled the CLA check for hamster and hamster-shell-extension. Please excuse the noise.

[GeraldJansen]

Okay, the comment is gone, but I still see "Some checks haven't completed yet" and "license/cla pending".

[elbenfreund]

Yes. As explained in this comment this will probably change once another push is triggered. Anyway, it is not a mandatory check, so it should not impose on anyone's work.

[elbenfreund]

Looking good :)

[ederag]

Good, there must never be a CLA on this repo.
At least my contributions are pure GPL.

I was curious about the origin of this bug, see #580.

[GeraldJansen]

Closed in favour of better #580. Yay!