Update to new ESMValTool logo

[axel-lauer]

Added new ESMValTool logo (as pdf and png) and updated doc/sphinx/source/conf.py accordingly. At the moment, the old "legacy" logo is also still present but not used.

[valeriupredoi]

do you think it'd be good to add a license/copyright to the figure? It is your/our creation after all

[valeriupredoi]

note that the logo doesn't show in README, https://github.com/ESMValGroup/ESMValTool/blob/master/doc/sphinx/source/figures/ESMValTool-logo-2.png gives a 404

[axel-lauer]

do you think it'd be good to add a license/copyright to the figure? It is your/our creation after all

So far, I thought since the ESMValTool is released under the Apache License, Version 2.0, this would automatically also cover things such as the logo or documentation. I also thought that the copyrights listed in https://github.com/ESMValGroup/ESMValTool/blob/master/NOTICE should apply to the whole package, but I might be wrong. Does anyone know if that's the case?

[axel-lauer]

note that the logo doesn't show in README, https://github.com/ESMValGroup/ESMValTool/blob/master/doc/sphinx/source/figures/ESMValTool-logo-2.png gives a 404

I kind of presumed this would be automatically resolved once the branch is merged into master. If not, I would appreciate some help with this.

[valeriupredoi]

do you think it'd be good to add a license/copyright to the figure? It is your/our creation after all

So far, I thought since the ESMValTool is released under the Apache License, Version 2.0, this would automatically also cover things such as the logo or documentation. I also thought that the copyrights listed in https://github.com/ESMValGroup/ESMValTool/blob/master/NOTICE should apply to the whole package, but I might be wrong. Does anyone know if that's the case?

Logos are a bit special - the licenses they go under are more restrictive than creative commons - here's an explanation - now, do we want to go the long way and license it?

[valeriupredoi]

note that the logo doesn't show in README, https://github.com/ESMValGroup/ESMValTool/blob/master/doc/sphinx/source/figures/ESMValTool-logo-2.png gives a 404

I kind of presumed this would be automatically resolved once the branch is merged into master. If not, I would appreciate some help with this.

yes, but I wanted to see it how it looks in the README before the merge, here, it looks terrific, love it 😍

[valeriupredoi]

well, apart from the eyesore that the FAILED CI test is 🤣

[valeriupredoi]

love the new logo! but before we merge we need to think about the license thingie