Cache npm dependencies in CI

Author: fwcd

.github/workflows/build.yml

@@ -4,15 +4,13 @@ on: [push]
 jobs:
   build:
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        node: ['12']
     steps:
       - uses: actions/checkout@v2
       - name: Set up Node
         uses: actions/setup-node@v2
         with:
-          node-version: ${{ matrix.node }}
+          node-version: '12'
+          cache: 'npm'
       - name: Install dependencies
         run: npm install
       - name: Compile grammar

.github/workflows/deploy-to-crates-io.yml

@@ -13,6 +13,7 @@ jobs:
         uses: actions/setup-node@v2
         with:
           node-version: '12'
+          cache: 'npm'
       - name: Install dependencies
         run: npm install
       - name: Compile grammar

.github/workflows/deploy-to-npm.yml

@@ -14,6 +14,7 @@ jobs:
         with:
           node-version: '12'
           registry-url: 'https://registry.npmjs.org'
+          cache: 'npm'
       - name: Install dependencies
         run: npm install
       - name: Compile grammar