Update 'Dockerfile'

Dockerfile

@@ -1,6 +1,8 @@
 # Install the base requirements for the app.
 # This stage is to support development.
 ARG BUILDPLATFORM="linux/amd64"
+ARG TARGETPLATFORM="linux/amd64"
+
 FROM --platform=$BUILDPLATFORM python:alpine AS base
 WORKDIR /app
 COPY requirements.txt .