Upgrade action to use node20 (#121)

* Action update:

- Bump all dependencies
- Rewrite `getLatestHelmVersion()` function without graphql

* Bump stableHelmVersion

* Update readme and action.yaml

* Revert and rewrite with @octokit/action

* Add latest to integration test

* Bump action's versions

* Set github.token as default input

* Replace deprecated jest methods

* Add prettier to dev dependencies, fix prettier issues

package.json

@@ -10,9 +10,8 @@
       "@actions/exec": "^1.1.1",
       "@actions/io": "^1.1.2",
       "@actions/tool-cache": "2.0.1",
-      "@octokit/auth-action": "^2.0.0",
-      "@octokit/graphql": "^4.6.1",
-      "semver": "^6.1.0"
+      "@octokit/action": "^6.0.7",
+      "semver": "^7.5.4"
    },
    "main": "lib/index.js",
    "scripts": {
@@ -23,11 +22,12 @@
       "format-check": "prettier --check ."
    },
    "devDependencies": {
-      "@types/jest": "^26.0.0",
-      "@types/node": "^12.0.10",
-      "@vercel/ncc": "^0.34.0",
-      "jest": "^26.0.1",
-      "ts-jest": "^26.0.0",
-      "typescript": "^3.5.2"
+      "@types/jest": "^29.5.11",
+      "@types/node": "^20.11.8",
+      "@vercel/ncc": "^0.38.1",
+      "jest": "^29.7.0",
+      "prettier": "^3.2.5",
+      "ts-jest": "^29.1.2",
+      "typescript": "^5.3.3"
    }
 }