Yarn v3, yarn cache and add windows to test matrix on gh

[klippx]

• yarn v3 (not plug n play - yet)
• yarn cache
• remove appveyor config
• test windows on GH

[changeset-bot]

⚠️ No Changeset found

Latest commit: 505f7a8

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[tulios]

We removed appveyor and node 14.x. The check will not be present on future builds.