fix: revert "use node24 as runner" (#278)

Reverts actions/create-github-app-token#267 and fixes
https://github.com/actions/create-github-app-token/issues/274.

.github/workflows/test.yml

@@ -38,7 +38,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: 24
+          node-version: 20
           cache: "npm"
       - run: npm ci
       - run: npm run build

.node-version

@@ -1 +1 @@
-24.4.0
+20.9.0

action.yml

@@ -132,6 +132,6 @@ outputs:
   app-slug:
     description: "GitHub App slug"
 runs:
-  using: "node24"
+  using: "node20"
   main: "dist/main.cjs"
   post: "dist/post.cjs"

package.json

@@ -5,7 +5,7 @@
   "version": "2.1.0",
   "description": "GitHub Action for creating a GitHub App Installation Access Token",
   "scripts": {
-    "build": "esbuild main.js post.js --bundle --outdir=dist --out-extension:.js=.cjs --platform=node --target=node24.0.0 --packages=bundle",
+    "build": "esbuild main.js post.js --bundle --outdir=dist --out-extension:.js=.cjs --platform=node --target=node20.0.0 --packages=bundle",
     "test": "c8 --100 ava tests/index.js",
     "coverage": "c8 report --reporter html",
     "postcoverage": "open-cli coverage/index.html"