fix: correct repository URLs and docstring examples

[golldyck]

Problem

pyproject.toml repository URLs point to langchain-ai/langchain instead of OpenGradient/og-langchain, causing PyPI and GitHub to link to the wrong project. Docstring examples in toolkits.py contain errors that cause TypeError when copied by developers.

Fix

Updated all repository URLs to point to the correct OpenGradient repo. Fixed docstring examples to use correct function signatures and type hints.

Changes

• pyproject.toml — Changed repository URL and Source Code URL from langchain-ai/langchain to OpenGradient/og-langchain
• langchain_opengradient/toolkits.py — Removed non-existent tool_type parameter from create_read_workflow_tool docstring example, fixed GetInputData() → GetInputData (reference not call) in create_run_model_tool docstring, corrected model_input_provider type hint from InferenceResult to dict

Testing

• Verified URLs resolve to the correct repository
• Confirmed docstring examples match actual method signatures
• Checked type hints are consistent with runtime behavior

Closes #2

[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!