chore: remove yarn cache

[joshuaellis]

Why

Codesandbox CI has a repo size limit that react-spring is hitting (see codesandbox/codesandbox-client#5872 (comment)).

What

• removes the cache in .yarn
• remove cache from gitignore so it's not readded.

Checklist

• Documentation updated
• Demo added
• Ready to be merged

[vercel]

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Name	Status	Preview	Updated
react-spring-io	✅ Ready (Inspect)	Visit Preview	Jul 21, 2022 at 6:02PM (UTC)

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

Latest deployment of this branch, based on commit 6b77bfe:

Sandbox	Source
spring-animating-auto	Configuration
spring-card	Configuration
spring-cards-stack	Configuration
spring-chain	Configuration
spring-css-keyframes	Configuration
spring-draggable-list	Configuration
spring-exit-before-enter	Configuration
spring-flip-card	Configuration
spring-goo-blobs	Configuration
spring-image-fade	Configuration
spring-list-reordering	Configuration
spring-masonry	Configuration
spring-multistage-transition	Configuration
spring-notification-hub	Configuration
spring-notification-hub	Configuration
spring-notification-hub	Configuration
initial-rocket	Configuration
spring-simple-transition	Configuration
spring-svg-filter	Configuration
spring-slide	Configuration
spring-tree	Configuration
spring-viewpager	Configuration