feat(gatsby-plugin-sharp): reduce encoding time and install size

[lovell]

Description

• Upgrades sharp to v0.29.0
• Replaces use of imagemin with sharp equivalents
• Removes GPLv3 code from the dependency graph
• Reduces JPEG, PNG and AVIF encoding time by up to 50%
• Reduces total Gatsby install size/time by ~10% (~19MB smaller on the filesystem)
• Improves AVIF image quality, will allow them to work with Chrome 93+
  AVIF files produces are invalid and not displayed by recent Chrome Canary lovell/sharp#2666

Related Issues

Fixes #31792

[lovell]

The windows_unit_tests failure is, I suspect, due to the use of a (shared?) npm cache in CircleCI colliding with lovell/sharp#2848. If there's a way to manually clear this cache then it should work when re-run.

[LekoArts]

Removes GPLv3 code from the dependency graph

So this is in our plugin, not sharp itself?

[lovell]

So this is in our plugin, not sharp itself?

Yes, this PR removes the GPLv3 pngquant-bin dependency from Gatsby via the removal of imagemin-pngquant. sharp has never shipped GPL code, and now provides the same features via the BSD-2-Clause https://github.com/lovell/libimagequant

[pieh]

The windows_unit_tests failure is, I suspect, due to the use of a (shared?) npm cache in CircleCI colliding with lovell/sharp#2848. If there's a way to manually clear this cache then it should work when re-run.

I checked syncinc version of sharp used in all packages and that seemed to the trick ( #32852 temporary PR that runs those tests with my small change). I opened PR with this change against your branch in lovell#1 (tho I didn't yet check wether there are any breaking changes in 0.29 those other packages might need to address)

[LekoArts]

Thanks! We'll merge and publish under next tag and before the 3.13 release check is everything works :) Thanks for your work!