fix: remove pytest-retry to avoid conflicting retry plugins

- Remove pytest-retry from dev dependencies in pyproject.toml
- Add pytest-xdist as proper dev dependency (was only in pip install)
- Update CI workflow to reflect proper dependency management
- Prevents conflict between pytest-retry and pytest-rerunfailures

Having both pytest-retry and pytest-rerunfailures installed simultaneously
causes unpredictable behavior and excessive retries.

.github/workflows/test-litellm-matrix.yml

@@ -89,9 +89,8 @@ jobs:
         run: |
           poetry config virtualenvs.in-project true
           poetry install --with dev,proxy-dev --extras "proxy semantic-router"
-          # pytest-rerunfailures is in pyproject.toml (v14.0 for Python 3.9 compat)
-          # pytest-xdist is required for -n (parallel workers) flag
-          poetry run pip install pytest-xdist google-genai==1.22.0 \
+          # pytest-rerunfailures and pytest-xdist are in pyproject.toml dev dependencies
+          poetry run pip install google-genai==1.22.0 \
             google-cloud-aiplatform>=1.38 fastapi-offline==1.7.3 python-multipart==0.0.22 openapi-core
 
       - name: Setup litellm-enterprise

pyproject.toml

@@ -151,7 +151,7 @@ pytest = "^7.4.3"
 pytest-mock = "^3.12.0"
 pytest-asyncio = "^0.21.1"
 pytest-postgresql = "^6.0.0"
-pytest-retry = "^1.6.3"
+pytest-xdist = "^3.5.0"
 requests-mock = "^1.12.1"
 responses = "^0.25.7"
 respx = "^0.22.0"