fix: add missing dependencies and correct badge URLs

[golldyck]

Problem

pyproject.toml is missing requests-toolbelt and httpx as direct dependencies, causing ImportError when users install the SDK via pip and use ModelHub.upload() or the LLM/twins clients. Additionally, README CI badge URLs point to a non-existent OpenGradient/sdk repo.

Fix

Added the missing dependencies to pyproject.toml, corrected the Ruff target-version to match requires-python, fixed CI badge URLs, and removed unreachable code in cli.py.

Changes

• pyproject.toml — Added requests-toolbelt and httpx to [project.dependencies], changed Ruff target-version from "py310" to "py311" to match requires-python = ">=3.11"
• README.md — Fixed CI badge URLs from OpenGradient/sdk to OpenGradient/OpenGradient-SDK
• src/opengradient/cli.py — Removed unreachable code after raise NotImplementedError in generate_image

Testing

• Verified requests-toolbelt and httpx are listed in dependencies
• Confirmed badge URLs resolve correctly
• Checked no functional code was removed from cli.py

Closes #265

[golldyck]

Hi @adambalogh @kylexqian — this PR fixes bugs I found during a full audit of OpenGradient's public repositories. Would appreciate a review when you get a chance. Happy to address any feedback. Thanks!

[kylexqian]

Need to update the uv.lock as well -- do you mind doing this?

[golldyck]

Done! Updated the uv.lock file to include the newly added dependencies (httpx and requests-toolbelt). Please check if everything looks good.