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

.github/workflows/unit-tests.yml

@@ -13,7 +13,7 @@ jobs:
    build: # make sure build/ci works properly
       runs-on: ubuntu-latest
       steps:
-         - uses: actions/checkout@v3
+         - uses: actions/checkout@v4
 
          - name: Run L0 tests.
            run: |