add mime type, fixes static files not loading when using reverse proxy

Dockerfile

@@ -3,7 +3,7 @@ FROM python:3.9-slim as builder
 
 COPY ./requirements.txt /requirements.txt
 
-RUN apt-get update && apt-get install -y --no-install-recommends g++ gosu && \
+RUN apt-get update && apt-get install -y --no-install-recommends g++ && \
     pip install --extra-index-url https://www.piwheels.org/simple --target=/dependencies -r /requirements.txt
 
 
@@ -14,7 +14,14 @@ ENV PYTHONUNBUFFERED=1
 
 COPY --from=builder /dependencies /usr/local
 ENV PYTHONPATH=/usr/local
-COPY --from=builder /usr/sbin/gosu /usr/sbin/gosu
+
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    # step down from root on entrypoint
+    gosu \
+	# add mime types for static files
+	mime-support && \
+	apt-get clean && rm -rf /var/lib/apt/lists/* && apt-get autoremove
 
 WORKDIR /app