fix: fix build by updating sitemap, RSS handler, and switching to bun

- Update @astrojs/sitemap 3.1.1 → 3.2.1 to fix destinationDir absolute path error
- Rename RSS handler `get` → `GET` for Astro 4.x compatibility
- Switch CI from yarn to bun

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: igorvieira

.github/workflows/astro.yml

@@ -21,5 +21,8 @@ jobs:
         with:
           node-version: ${{ matrix.node-version }}
 
-      - run: yarn --frozen-lockfile
-      - run: yarn build
+      - name: Install bun
+        uses: oven-sh/setup-bun@v2
+
+      - run: bun install --frozen-lockfile
+      - run: bun run build

bun.lockb

@@ -13,7 +13,7 @@
     "@astrojs/mdx": "2.2.0",
     "@astrojs/react": "^4.4.2",
     "@astrojs/rss": "4.0.5",
-    "@astrojs/sitemap": "3.1.1",
+    "@astrojs/sitemap": "3.2.1",
     "@types/react": "^18.0.21",
     "@types/react-dom": "^18.0.6",
     "astro": "4.5.5",

package.json

@@ -2,7 +2,7 @@ import rss from "@astrojs/rss";
 import { getCollection } from "astro:content";
 import { SITE_DESCRIPTION } from "../consts";
 
-export async function get(context) {
+export async function GET(context) {
   const posts = await getCollection("blog");
   return rss({
     title: "🍋 Igor Vieira",