fix: remove serverClientId warning, change in .env.template

[abhinavs1920]

… .env.template

Description

This PR updates the .env.template to use SERVER_CLIENT_ID instead of GOOGLE_SIGNIN_ANDROID_CLIENT_ID to address the warning message generated during Google Sign-In implementation on Android. This change ensures that the application follows best practices and reduces unnecessary noise in the logs. The update also prepares the application for future versions of the Google Sign-In SDK that might deprecate the fallback behavior.

Fixes #212

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactor (does not change functionality, e.g. code style improvements, linting)
• Documentation update

How Has This Been Tested?

The changes have been tested by setting up the application with the updated .env.template, configuring Google Sign-In, and verifying that the warning message no longer appears in the Android logs during the sign-in process.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings

Maintainer Checklist

• closes #xxxx (Replace xxxx with the GitHub issue number)
• Tag the PR with the appropriate labels

[mdmohsin7]

@abhinavs1920 can you check this once and see do we even need it at all or can omit it?
flutter/flutter#107532

[abhinavs1920]

@mdmohsin7, Yes after reading the thread, I would say we can go with the changes as for android only the above change is required. I have also verified the logs after change, it does not give the warning anymore.