Update Copernicus to v6.4 and add missing Copernicus journal

[RLumSK]

Another update of the Copernicus template (now version 6.4) and I've added a so far missing journal ("Web Ecology") to copernicus_article()

• Update NEWS.

[RLumSK]

@nuest Sorry, I forgot to ping you for this PR.

[RLumSK]

@cderv The failed CI checks do not seem to be related to my PR.

[cderv]

Yes I agree. It seems to be from the Glossa format.

our test suites runs every format for now. It would be interesting to only test the modified format for PR 🤔

[RLumSK]

@cderv Thanks for the prompt response. For what it is worth, I have tested the modified version, only the Copernicus template, manually on my computer (macOS 11.6.1, pandoc 2.16.1, R 4.1.1). No problem here, but perhaps this is not a replacement for the full tests you run.

[cderv]

Looks good overall apart from a comment I left above.

After you answer and possibly change, we are good to merge

[RLumSK]

@cderv Thanks for your support and the critical PR review! You raised an important point I had overlooked, at least now we have tested that and I can keep an eye on it, in case it causes some problems in the future.