[google-genai] Test instrumentation on google-genai v1.64.0

[Rima-ag]

Description

Bumps google-genai package to v1.64.0.

1. Tests were failing because http method is recorded in cassette in upper case but is generated in the test in lower case, so the request method was standardised to upper case in the tests
2. async tests were hanging because, when releasing v1.64.0, google-genai set aiohttp >= 3.10.11 and the vcrpy aiohttp mock stub is not compatible with how google-genai is reading the stream (related issue Latest google-genai + aiohttp gets into infinite loop when streaming from VCR cassette kevin1024/vcrpy#927):
   • The stub content used to create a stream object at every single call, which is not compatible with google-genai's way of reading the stream with readline
   • When the request is closed, aiohttp throws a ClientConnectionError that can be ignore in the context of cassette tests

Fixes #4240

Type of change

• Tests
• 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)
• This change requires a documentation update

How Has This Been Tested?

• Unit Tests

Does This PR Require a Core Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

See contributing.md for styleguide, changelog guidelines, and more.

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated