Move build workflow from CircleCI to GitHub Actions

.github/actions/node/12/action.yml

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+name: Node 12
+runs:
+  using: composite
+  steps:
+    - uses: actions/setup-node@v3
+      with:
+        node-version: '12'

.github/actions/node/14/action.yml

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+name: Node 14
+runs:
+  using: composite
+  steps:
+    - uses: actions/setup-node@v3
+      with:
+        node-version: '14'

.github/actions/node/16/action.yml

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+name: Node 16
+runs:
+  using: composite
+  steps:
+    - uses: actions/setup-node@v3
+      with:
+        node-version: '16'

.github/actions/node/17/action.yml

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+name: Node 17
+runs:
+  using: composite
+  steps:
+    - uses: actions/setup-node@v3
+      with:
+        node-version: '17'

.github/actions/node/latest/action.yml

@@ -0,0 +1,7 @@
+name: Node 17
+runs:
+  using: composite
+  steps:
+    - uses: actions/setup-node@v3
+      with:
+        node-version: '17'

.github/actions/node/oldest/action.yml

@@ -0,0 +1,7 @@
+name: Node 12
+runs:
+  using: composite
+  steps:
+    - uses: actions/setup-node@v3
+      with:
+        node-version: '12'

.github/actions/node/setup/action.yml

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+name: Node Setup
+runs:
+  using: composite
+  steps:
+    - uses: actions/setup-node@v3
+      with:
+        cache: yarn

.github/workflows/core.yml

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+name: Core
+
+on:
+  push:
+  schedule:
+    - cron: '0 4 * * *'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref || github.run_id }}
+  cancel-in-progress: true
+
+jobs:
+  shimmer:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ./.github/actions/node/setup
+      - run: yarn install
+      - uses: ./.github/actions/node/oldest
+      - run: yarn test:shimmer:ci
+      - uses: ./.github/actions/node/latest
+      - run: yarn test:shimmer:ci
+      - run: yarn codecov