Fix Botocore test compatibility with newer aiohttp

[Shriprasad-P]

Description

Botocore aiobotocore test envs can fail when an older transitive vcrpy
is resolved against newer aiohttp (AsyncStreamReaderMixin missing).

Pin vcrpy==8.3.0 in test-requirements-2.txt and
test-requirements-3.txt so the compatible VCR release is explicit.
Test-only change; no runtime dependency impact.

Fixes #4645

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• tox run -r -e py312-test-instrumentation-botocore-2,py312-test-instrumentation-botocore-3 -- -q --tb=line (143 passed, 1 skipped)

Does This PR Require a Core Repo Change?

• No.

Checklist:

• Followed the style guidelines of this project
• Changelogs have been updated (Skip Changelog — test dependency pin only)
• Unit tests have been added (existing VCR-backed suite covers this)
• Documentation has been updated

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: Shriprasad-P / name: Shriprasad (ece9a01)

[Shriprasad-P]

Updated the branch onto current main. The Botocore test environments pass locally (143 passed, 1 skipped), and the PR remains limited to the two test requirement files.

This pins vcrpy==8.3.0 so the aiohttp / AsyncStreamReaderMixin compatibility issue cannot recur through a floating transitive resolve. This is a test-only change, so Skip Changelog should apply.

The CI and changelog workflows are currently waiting for approval. Could a maintainer approve them and take a look when convenient?