fix: handle clock skew (#87)

GitHub's macOS runners for the past while have had some bad clock drift
which sometimes prevents this action from working with the error:

```console
'Issued at' claim ('iat') must be an Integer representing the time that the assertion was issued
```

`@octokit/auth-app` already has logic to handle this so we can defer to
that code.

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "create-github-app-token",
-  "version": "1.6.0",
+  "version": "1.6.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "create-github-app-token",
-      "version": "1.6.0",
+      "version": "1.6.1",
       "license": "MIT",
       "dependencies": {
         "@actions/core": "^1.10.1",
@@ -15,6 +15,7 @@
         "p-retry": "^6.1.0"
       },
       "devDependencies": {
+        "@sinonjs/fake-timers": "^11.2.2",
         "ava": "^5.3.1",
         "c8": "^8.0.1",
         "dotenv": "^16.3.1",
@@ -811,6 +812,24 @@
         "@octokit/openapi-types": "^19.0.0"
       }
     },
+    "node_modules/@sinonjs/commons": {
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/@sinonjs/commons/-/commons-3.0.0.tgz",
+      "integrity": "sha512-jXBtWAF4vmdNmZgD5FoKsVLv3rPgDnLgPbU84LIJ3otV44vJlDRokVng5v8NFJdCf/da9legHcKaRuZs4L7faA==",
+      "dev": true,
+      "dependencies": {
+        "type-detect": "4.0.8"
+      }
+    },
+    "node_modules/@sinonjs/fake-timers": {
+      "version": "11.2.2",
+      "resolved": "https://registry.npmjs.org/@sinonjs/fake-timers/-/fake-timers-11.2.2.tgz",
+      "integrity": "sha512-G2piCSxQ7oWOxwGSAyFHfPIsyeJGXYtc6mFbnFA+kRXkiEnTl8c/8jul2S329iFBnDI9HGoeWWAZvuvOkZccgw==",
+      "dev": true,
+      "dependencies": {
+        "@sinonjs/commons": "^3.0.0"
+      }
+    },
     "node_modules/@tokenizer/token": {
       "version": "0.3.0",
       "resolved": "https://registry.npmjs.org/@tokenizer/token/-/token-0.3.0.tgz",
@@ -4089,6 +4108,15 @@
         "node": ">=0.6.11 <=0.7.0 || >=0.7.3"
       }
     },
+    "node_modules/type-detect": {
+      "version": "4.0.8",
+      "resolved": "https://registry.npmjs.org/type-detect/-/type-detect-4.0.8.tgz",
+      "integrity": "sha512-0fr/mIH1dlO+x7TlcMy+bIDqKPsw/70tVyeHW787goQjhmqaZe10uwLujubK9q9Lg6Fiho1KUKDYz0Z7k7g5/g==",
+      "dev": true,
+      "engines": {
+        "node": ">=4"
+      }
+    },
     "node_modules/type-fest": {
       "version": "0.13.1",
       "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-0.13.1.tgz",