Cache yarn global package data in CI

[dacook]

I set out to cache the node_modules folder, but came across this easy fix first: https://github.com/actions/setup-node?tab=readme-ov-file#caching-global-packages-data
I don't know what this actually does, because it doesn't install the dependencies, that still needs to happen next.
But it saves about 6 seconds (see results below), so I think it's worth adding.

What should we test?

• green specs
• spec time slightly reduced

Next up

We could probably save a further 6 seconds by caching node_modules. This guide looks straightforward. But why is this not built-in to an official action??
https://github.com/actions/cache/blob/main/examples.md#node---yarn

[dacook]

I checked and this saves about 6 seconds, so I think it's worth adding.

Before (last build on master) - 19s

First time - 22s

Run actions/setup-node@v3:

/usr/local/bin/yarn --version
1.22.22
/usr/local/bin/yarn cache dir
/home/runner/.cache/yarn/v6
/usr/local/bin/yarn config get enableGlobalCache
undefined
yarn cache is not found

Subsequent - 13s

Run actions/setup-node@v3:

/usr/local/bin/yarn --version
1.22.22
/usr/local/bin/yarn cache dir
/home/runner/.cache/yarn/v6
/usr/local/bin/yarn config get enableGlobalCache
undefined
Cache Size: ~61 MB (64041350 B)
/usr/bin/tar -xf /home/runner/work/_temp/46850132-e5ba-4cb4-8a8c-c3e49a8e9c1c/cache.tzst -P -C /home/runner/work/openfoodnetwork/openfoodnetwork --use-compress-program unzstd
Received 64041350 of 64041350 (100.0%), 61.0 MBs/sec
Cache restored successfully
Cache restored from key: node-cache-Linux-yarn-e[27](https://github.com/dacook/openfoodnetwork/actions/runs/9558250039/job/26347954244#step:7:29)235ce2c8781[28](https://github.com/dacook/openfoodnetwork/actions/runs/9558250039/job/26347954244#step:7:30)9663c75b62dc60a2001f09009fbbdc89361a70596f9ddfbd

https://github.com/dacook/openfoodnetwork/actions/runs/9558250039/job/26347954244

[rioug]

I don't know what this actually does, because it doesn't install the dependencies, that still needs to happen next.

Presumably it caches the downloaded dependencies, which are then installed from the cache, see :
https://github.com/actions/setup-node/blob/main/docs/advanced-usage.md#caching-packages-data

[rioug]

Nice find !

[mkllnk]

Nice!