Added Automated API Test Suite

[trivedikavya]

This Pr is related to #1442 in This PR introduces a comprehensive automated test suite (test_all_endpoints.py) for the AgriTech backend. It allows developers to quickly verify that all ML models and API endpoints are functioning correctly after changes.

Key Features

• Module Coverage: Includes tests for Crop Recommendation, Yield Prediction, Fertilizer Suggestion, and Disease Detection.
• Robust Error Handling: Added tests for edge cases like missing JSON fields and empty file uploads.
• Performance & Quality: Integrated checks for response latency (threshold < 5s) and valid JSON formatting.
• Batch Testing: Added a utility to run multiple predictions from a sample_crop_input.json file to check model accuracy over time.
• Custom Test Runner: Provides a clean, formatted terminal output with a final summary of PASS/FAIL/SKIP statuses.

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[github-actions]

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[github-actions]

🎉 Congrats @trivedikavya on getting your PR merged! 🙌
Thanks for the contribution — looking forward to more from you 🚀