fix(deps): update jsonwebtoken to v9 (#68)

Author: gr2m

.github/workflows/test.yml

@@ -10,9 +10,5 @@ jobs:
         with:
           node-version: 18
           cache: npm
-      - name: Install playwright browsers
-        run: npx playwright install --with-deps
-      - name: Run tests
-        run: npx playwright test
       - run: npm ci
       - run: npm test

README.md

@@ -68,7 +68,7 @@ const { githubAppJwt } = require("universal-github-app-jwt");
 (async () => {
   const { token, appId, expiration } = await githubAppJwt({
     id: APP_ID,
-    privateKey: PRIVATE_KEY
+    privateKey: PRIVATE_KEY,
   });
 })();
 ```
@@ -78,8 +78,8 @@ The retrieved `token` can now be used in Authorization request header, e.g. with
 ```js
 request("GET /app", {
   headers: {
-    authorization: `bearer ${token}`
-  }
+    authorization: `bearer ${token}`,
+  },
 });
 ```