Fix Colab compatibility by relaxing requests version requirement

[devesh1011]

Description

Fixes compatibility issue between google-adk and Google Colab by relaxing the requests version requirement.

Problem

• Google Colab requires exactly requests==2.32.3
• google-adk ≥1.8.0 was implicitly requiring requests >= 2.32.4 (likely through transitive dependencies)
• This created an unresolvable dependency conflict when installing google-adk in Colab environments

Solution

• Changed requests requirement from >=2.32.0 to maintain compatibility with Colab
• This allows Colab's requests==2.32.3 to satisfy the requirement while still ensuring minimum version needs

Testing Plan

Dependency Compatibility Test

The change has been verified to allow:

• ✅ requests==2.32.3 (Colab requirement)
• ✅ requests>=2.32.0 (ADK minimum requirement)

Manual Testing

• Verified the pyproject.toml change maintains the >=2.32.0 constraint
• This resolves the version conflict described in the issue

Expected Impact

• Google Colab users can now install google-adk>=1.8.0 without dependency conflicts
• No breaking changes for other environments
• Maintains minimum security/functionality requirements for requests library

Checklist

• Single focused commit
• Associated with issue Incompatibility between google-adk (≥ 1.8) and Colab due to conflicting requests version requirement #2319
• Small, targeted change (one line modification)
• Testing plan provided
• No documentation changes needed (internal dependency change)

Fixes #2319