Fix leap year handling in VDI

[jnettels]

A hardcoded number of minutes per year prevented leap years from being constructed properly. This is fixed by using the hoy. Also there was a test test_leap_year(), but it did not actually test a leap year.
This should fix those issues.

[p-snft]

Thanks for fixing this.

PS: You might want to add this to the changelog.

[jnettels]

Hi, should I update CHANGELOG.rst within this PR? Or should I do a new PR with the changes for both of my approved PRs, to avoid the merge conflict that would probably happen if I update the changelog within both PRs? Thanks

[p-snft]

Hi, should I update CHANGELOG.rst within this PR? Or should I do a new PR with the changes for both of my approved PRs, to avoid the merge conflict that would probably happen if I update the changelog within both PRs? Thanks

Every PR with significant changes should include a documentation in the changelog. (Yes, that means that you have to resolve conflicts from time to time, but in this case it should just be "accept both".)

[jnettels]

Ok thanks, seems like "accept both" worked just fine.