Revert "Factor out the bootstrapping steps into a reusable action (#188)"

This reverts the previous two commits, because I learned the hard way
that actions cannot be composed out of other actions.

Author: jgonggrijp

.github/actions/bootstrap/action.yml

@@ -18,8 +18,28 @@ jobs:
 
     steps:
     - uses: actions/checkout@v2
-    - uses: ./.github/actions/bootstrap
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v1
       with:
         node-version: ${{ matrix.node-version }}
+    - name: Configure yarn cache path
+      run: yarn config set cache-folder ~/.yarn-cache
+    - name: Restore yarn cache
+      uses: actions/cache@v2
+      with:
+        path: ~/.yarn-cache
+        key: yarn-cache-${{ matrix.node-version }}
+        restore-keys: |
+          yarn-cache-
+    - name: Restore node_modules
+      uses: actions/cache@v2
+      with:
+        path: node_modules
+        key: node-modules-${{ matrix.node-version }}-${{ hashFiles('yarn.lock') }}
+        restore-keys: |
+          node-modules-${{ matrix.node-version }}-
+          node-modules-
+    - name: Install dependencies
+      run: yarn
     - name: Run linter, concat, minifier and tests
       run: yarn dist