Add altmetrics links and icons to publications page

[nuest]

Paperbuzz

If a DOI is available.

API docs: https://paperbuzz.org/api

Examples:

• https://paperbuzz.org/details/10.7557/5.4910 (API)
• https://paperbuzz.org/details/10.7717/peerj.5072 (API)

Altmetric

See https://twitter.com/benmarwick/status/1271863581223424000?s=09

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This requires to add some functions to the JavaScript in the file publications.md.

[nuest]

@NJaku01 Same here - if you need to relax from the bindings, please take a look at this little improvement for our website.