Update to use Yarn v3

While this project may ultimately switch back to using npm, or may opt
to use pnpm instead, Yarn 3 is a significant win for as long as this
app *is* using Yarn:

1. Yarn v3 is maintained; Yarn v1 is *not*. This is the most important
   reason to make this switch.

2. Yarn v2+ handles peer dependencies much more rigorously than Yarn v1
   (or npm), albeit not quite as well as pnpm. As part of the
   ecosystem's move to using properly Node-resolvable packages, we are
   increasingly making use of peer dependencies, so this is important
   future-readiness.

Author: chriskrycho

.github/workflows/ci.yml

@@ -7,7 +7,6 @@ on:
   pull_request:
 
 env:
-  NODE_VERSION: 12
   PERCY_PARALLEL_NONCE: ${{ github.run_id }}-${{ github.run_number }}
   PERCY_PARALLEL_TOTAL: 1
 
@@ -29,13 +28,13 @@ jobs:
 
       - name: Cache Yarn cache and node_modules
         id: cache-dependencies
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: |
             ${{ steps.yarn-cache-dir-path.outputs.dir }}
             node_modules
-          key: ${{ runner.os }}-${{ env.NODE_VERSION }}-${{ hashFiles('**/yarn.lock') }}
-          restore-keys: ${{ runner.os }}-${{ env.NODE_VERSION }}-
+          key: ${{ runner.os }}-yarn-${{ hashFiles('**/yarn.lock') }}
+          restore-keys: ${{ runner.os }}-yarn-
 
       - name: Install dependencies
         run: yarn install --frozen-lockfile
@@ -44,7 +43,6 @@ jobs:
       - name: Lint
         run: yarn lint
 
-
   test-app:
     name: Test app
     runs-on: ubuntu-latest
@@ -53,7 +51,7 @@ jobs:
       - name: Check out a copy of the repo
         uses: actions/checkout@v2
 
-      - name: Use Node.js 14
+      - name: Use Node.js v14
         uses: volta-cli/action@v4
 
       - name: Get Yarn cache path
@@ -62,13 +60,13 @@ jobs:
 
       - name: Cache Yarn cache and node_modules
         id: cache-dependencies
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: |
             ${{ steps.yarn-cache-dir-path.outputs.dir }}
             node_modules
-          key: ${{ runner.os }}-14-${{ hashFiles('**/yarn.lock') }}
-          restore-keys: ${{ runner.os }}-14-
+          key: ${{ runner.os }}-yarn-${{ hashFiles('**/yarn.lock') }}
+          restore-keys: ${{ runner.os }}-yarn-
 
       - name: Install dependencies
         run: yarn install --frozen-lockfile

.gitignore

@@ -15,6 +15,13 @@ terraform.tfstate.backup
 # dependencies
 /bower_components/
 /node_modules/
+.pnp.*
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/releases
+!.yarn/sdks
+!.yarn/versions
 
 # misc
 /.projectile

.yarnrc.yml

@@ -0,0 +1 @@
+nodeLinker: node-modules

package.json

@@ -134,6 +134,6 @@
   ],
   "volta": {
     "node": "14.17.0",
-    "yarn": "1.22.19"
+    "yarn": "3.3.0"
   }
 }