2901: Fix recurring dates yet again

[LeandraH]

Short description

When rewriting the recurrent dates a few weeks ago, I missed a test case: repeating an event every nth week of the month.

In that case, the recurrence rule gets the parameter BYDAY=+3TH. When parsing that, our package rrule turns that not into the parameter byweekday but into the parameter bynweekday (the n stands for nth weekday). When turning the parameter bynweekday back into a string, we get the parameter BYNWEEKDAY=3,+3, which doesn't seem to be a valid parameter.

So I decided to stick to the string of the recurrence rule as the source of truth and not the recurrence rule object from our rrule package.

You can also see some fun workarounds in this issue: jkbrzt/rrule#326

Proposed changes

• Get the recurrence rule that has been offset by our timezone via the string of the rule, not the object from the package
• MORE TESTS (if you see more missing test cases, please tell me)

Side effects

• Hopefully none

Testing

Run the tests in your environment
Check particularly that events repeating every nth day (e.g. every 4th Friday) are showing correctly http://localhost:9000/testumgebung/de/events/test-monthly
Any other repeating event combinations that you can think of

Resolved issues

Fixes: #2901

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[steffenkleinle]

Works like a charm, thanks for fixing all this stuff! 💚

[LeandraH]

@ztefanie or @f1sh1918 it would be cool if one of you could still review this PR this week :)

[codeclimate]

Code Climate has analyzed commit b2b7a35 and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 100.0% (50% is the threshold).

This pull request will bring the total coverage in the repository to 74.0%.

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