Updating tools/vegan tool to 2.6_2 2.6_4 2.6_8

[planemo-autoupdate]

Hello! This is an automated update of the following tool: tools/vegan. I created this PR because I think the tool's main dependency is out of date, i.e. there is a newer version available through conda.

Please see https://github.com/planemo-autoupdate/autoupdate for more information.

[bernt-matthias]

https://cran.r-project.org/web/packages/vegan/news.html