ci: modernise workflow and fix lint for deprecation release

- Update actions/checkout and actions/setup-node to v4 (actions/cache v2 no longer functions)
- Use Node 20 with built-in yarn cache
- Add pull_request trigger so checks report on PRs
- Commit yarn.lock so --frozen-lockfile install succeeds
- Fix prettier formatting in src/migration.ts

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: ice-chillios

.github/workflows/typescript_and_lint.yml

@@ -4,24 +4,20 @@ on:
   push:
     branches:
       - "*"
+  pull_request:
 
 jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions/setup-node@v2
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
         with:
-          node-version: "16"
-
-      - uses: actions/cache@v2
-        id: yarn-cache
-        with:
-          path: "**/node_modules"
-          key: ${{ runner.os }}-modules-${{ hashFiles('**/yarn.lock') }}
+          node-version: "20"
+          cache: yarn
 
       - name: Install
-        run: yarn install --frozen-lockfile
+        run: yarn install --frozen-lockfile --ignore-engines
 
       - name: Lint
         run: yarn lint

src/migration.ts

@@ -43,8 +43,8 @@ export async function showMigrationNotice(
     extensions.getExtension(NEW_EXTENSION_ID) !== undefined
       ? FINISH_MESSAGE
       : lastShownAt === undefined
-        ? INITIAL_MESSAGE
-        : REMINDER_MESSAGE,
+      ? INITIAL_MESSAGE
+      : REMINDER_MESSAGE,
   );
 }