Update GitHub actions to use Node.js 20

Author: benfrancis

.github/workflows/build.yml

@@ -14,9 +14,7 @@ jobs:
     strategy:
       matrix:
         node-version: [
-          10,
-          12,
-          14,
+          20
         ]
     steps:
       - uses: actions/checkout@v2

.github/workflows/release.yml

@@ -14,7 +14,7 @@ jobs:
 
       - uses: actions/setup-node@v1
         with:
-          node-version: 10
+          node-version: 20
           registry-url: 'https://registry.npmjs.org'
 
       - name: Set release version