add d2

[moritzwilksch]

Checklist

• Title of this PR is meaningful: e.g. "Adding my_nifty_package", not "updated meta.yaml".
• License file is packaged (see here for an example).
• Source is from official source.
• Package does not vendor other packages. (If a package uses the source of another package, they should be separate packages or the licenses of all packages need to be packaged).
• If static libraries are linked in, the license of the static library is packaged.
• Package does not ship static libraries. If static libraries are needed, follow CFEP-18.
• Build number is 0.
• A tarball (url) rather than a repo (e.g. git_url) is used in your recipe (see here for more details).
• GitHub users listed in the maintainer section have posted a comment confirming they are willing to be listed there.
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[github-actions]

Hi! This is the staged-recipes linter and your PR looks excellent! 🚀

[conda-forge-admin]

Hi! This is the friendly automated conda-forge-linting service.

I wanted to let you know that I linted all conda-recipes in your PR (recipes/d2/recipe.yaml) and found some lint.

Here's what I've got...

For recipes/d2/recipe.yaml:

• ❌ The homepage item is expected in the about section.
• ❌ The summary item is expected in the about section.
• ❌ There are too few lines. There should be one empty line at the end of the file.
• ❌ This recipe is using a compiler, which now requires adding a build dependence on ${{ stdlib("c") }} as well. Note that this rule applies to each output of the recipe using a compiler. For further details, please see META: {{ stdlib("c") }} migration conda-forge.github.io#2102.

[conda-forge-admin]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipes/d2/recipe.yaml) and found it was in an excellent condition.