Upgrade Astro to v4 and refactor tests to ESM (#95)

.github/workflows/ci.yml

@@ -21,14 +21,14 @@ jobs:
       - name: Setup Node
         uses: actions/setup-node@v3
         with:
-          node-version: 16
+          node-version: 20
           cache: npm
 
       - name: Install Dependencies
         run: npm ci
 
       - name: Test
-        run: npm run test:ci
+        run: npm t
 
   lint:
     runs-on: ubuntu-latest
@@ -39,7 +39,7 @@ jobs:
       - name: Setup Node
         uses: actions/setup-node@v3
         with:
-          node-version: 16
+          node-version: 20
           cache: npm
 
       - name: Install Dependencies

.github/workflows/release.yml

@@ -18,10 +18,10 @@ jobs:
           # This makes Actions fetch all Git history so that Changesets can generate changelogs with the correct commits
           fetch-depth: 0
 
-      - name: Setup Node.js 16.x
+      - name: Setup Node.js 20
         uses: actions/setup-node@v2
         with:
-          node-version: 16.x
+          node-version: 20
 
       - name: Cache node_modules
         uses: actions/cache@v2

.nvmrc

@@ -0,0 +1 @@
+20

demo/package.json

@@ -9,7 +9,7 @@
     "preview": "astro preview"
   },
   "devDependencies": {
-    "@astrojs/mdx": "^0.19.7",
-    "astro": "^2.8.3"
+    "@astrojs/mdx": "^2.2.2",
+    "astro": "^4.5.12"
   }
 }