Add required Debian dependencies to allow docker builds on the arm pl…

…atform (#8144)

Signed-off-by: Christopher May-Townsend <chris@maytownsend.co.uk>

changelog.d/8144.docker

@@ -0,0 +1 @@
+Fix builds of the Docker image on non-x86 platforms.

docker/Dockerfile

@@ -19,11 +19,16 @@ ARG PYTHON_VERSION=3.7
 FROM docker.io/python:${PYTHON_VERSION}-slim as builder
 
 # install the OS build deps
-
-
 RUN apt-get update && apt-get install -y \
     build-essential \
+    libffi-dev \
+    libjpeg-dev \
     libpq-dev \
+    libssl-dev \
+    libwebp-dev \
+    libxml++2.6-dev \
+    libxslt1-dev \
+    zlib1g-dev \
  && rm -rf /var/lib/apt/lists/*
 
 # Build dependencies that are not available as wheels, to speed up rebuilds
@@ -56,9 +61,11 @@ FROM docker.io/python:${PYTHON_VERSION}-slim
 
 RUN apt-get update && apt-get install -y \
     curl \
+    gosu \
+    libjpeg62-turbo \
     libpq5 \
+    libwebp6 \
     xmlsec1 \
-    gosu \
  && rm -rf /var/lib/apt/lists/*
 
 COPY --from=builder /install /usr/local