fix(tutorials): retry flaky PyPI fetches in pydantic_ai images

Both 110_pydantic_ai image builds failed four times when a PyPI download
dropped mid-stream during uv pip install, mostly in the emulated arm64
half. uv 0.6.4 doesn't retry that error. Retry the install up to three
times (10s, then 20s backoff) and lower parallel downloads to 4.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: danielmillerp

examples/tutorials/10_async/00_base/110_pydantic_ai/Dockerfile

@@ -21,6 +21,8 @@ RUN apt-get update && apt-get install -y \
 RUN uv pip install --system --upgrade pip setuptools wheel
 
 ENV UV_HTTP_TIMEOUT=1000
+# Fewer parallel PyPI downloads, so the slow emulated arm64 build drops fewer connections.
+ENV UV_CONCURRENT_DOWNLOADS=4
 
 # Copy pyproject.toml and README.md to install dependencies
 COPY 10_async/00_base/110_pydantic_ai/pyproject.toml /app/110_pydantic_ai/pyproject.toml
@@ -37,8 +39,15 @@ COPY 10_async/00_base/110_pydantic_ai/tests /app/110_pydantic_ai/tests
 # Copy shared test utilities
 COPY test_utils /app/test_utils
 
-# Install the required Python packages with dev dependencies
-RUN uv pip install --system .[dev] pytest-asyncio httpx
+# Install the required Python packages with dev dependencies.
+# Retried because PyPI downloads sometimes drop mid-stream, and this uv
+# version doesn't retry that error itself.
+RUN for attempt in 1 2 3; do \
+        uv pip install --system .[dev] pytest-asyncio httpx && exit 0; \
+        echo "uv pip install failed (attempt $attempt of 3)"; \
+        [ "$attempt" -lt 3 ] && sleep $((attempt * 10)); \
+    done; \
+    exit 1
 
 # Set environment variables
 ENV PYTHONPATH=/app

examples/tutorials/10_async/10_temporal/110_pydantic_ai/Dockerfile

@@ -21,6 +21,8 @@ RUN apt-get update && apt-get install -y \
 RUN uv pip install --system --upgrade pip setuptools wheel
 
 ENV UV_HTTP_TIMEOUT=1000
+# Fewer parallel PyPI downloads, so the slow emulated arm64 build drops fewer connections.
+ENV UV_CONCURRENT_DOWNLOADS=4
 
 COPY 10_async/10_temporal/110_pydantic_ai/pyproject.toml /app/110_pydantic_ai/pyproject.toml
 COPY 10_async/10_temporal/110_pydantic_ai/README.md /app/110_pydantic_ai/README.md
@@ -31,7 +33,14 @@ COPY 10_async/10_temporal/110_pydantic_ai/project /app/110_pydantic_ai/project
 COPY 10_async/10_temporal/110_pydantic_ai/tests /app/110_pydantic_ai/tests
 COPY test_utils /app/test_utils
 
-RUN uv pip install --system .[dev]
+# Retried because PyPI downloads sometimes drop mid-stream, and this uv
+# version doesn't retry that error itself.
+RUN for attempt in 1 2 3; do \
+        uv pip install --system .[dev] && exit 0; \
+        echo "uv pip install failed (attempt $attempt of 3)"; \
+        [ "$attempt" -lt 3 ] && sleep $((attempt * 10)); \
+    done; \
+    exit 1
 
 ENV PYTHONPATH=/app