chore: switch to pnpm and remove DISCORD_APP

.github/workflows/lint.yml

@@ -1,11 +1,23 @@
 name: Lint
 
-on: [push]
+on:
+  push:
+  pull_request:
 
 jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
-      - run: yarn install --frozen-lockfile
-      - run: yarn lint
+      - name: Checkout repository
+        uses: actions/checkout@v3
+      - name: Install Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: 20
+      - name: Install pnpm
+        uses: pnpm/action-setup@v2
+
+      - name: Install dependencies
+        run: pnpm install
+      - name: Lint
+        run: pnpm run lint