Improve Testing Coverage in gofr/pkg/gofr/datasource/pubsub/google file

[NitinKumar004]

The Google Cloud Pub/Sub datasource package currently has 44.5% test coverage. This package is a critical component for handling pub/sub messaging with Google Cloud Platform and requires comprehensive test coverage to ensure reliability and maintainability.

Improve test coverage for /pkg/gofr/datasource/pubsub/google package as much as possible. The goal is to maximize coverage for all code (excluding auto-generated mocks) while ensuring quality and meaningful tests.

[NitinKumar004]

@coolwednesday @Umang01-hash can you please assign to me.

[coolwednesday]

@NitinKumar004, Assigned the same to you.