Make backers.svg lazy-loading

[fuweichin]

Eruda will request a thirdparty website when initializing, which may cause console error due to use of same-origin Cross-Origin-Embeder-Policy, or due to lack of internet connection, e.g.

GET https://opencollective.com/eruda/backers.svg?width=1536&exclude=true net::ERR_BLOCKED_BY_RESPONSE.NotSameOriginAfterDefaultedToSameOriginByCoep 200 (OK)

It's annoyning to see error for every reload when debugging. A mitigation measure is to add attribute loading="lazy" for that <img>.

Also note that requesting a thirdparty website may voilate users' privacy without notice.