Harden Docker apt install with retry logic

Dockerfile

@@ -4,7 +4,9 @@ ENV PYTHONDONTWRITEBYTECODE=1 \
     PYTHONUNBUFFERED=1 \
     PIP_NO_CACHE_DIR=1
 
-RUN apt-get update && apt-get install -y --no-install-recommends \
+RUN set -eux; \
+    apt-get update -o Acquire::Retries=5; \
+    apt-get install -y --no-install-recommends -o Acquire::Retries=5 \
         build-essential \
         libpq-dev \
         curl \
@@ -22,8 +24,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
         libxdamage1 \
         libxfixes3 \
         libxrandr2 \
-    fonts-liberation \
-    && rm -rf /var/lib/apt/lists/*
+        fonts-liberation; \
+    rm -rf /var/lib/apt/lists/*
 
 WORKDIR /app