fix mitmproxy#6267 (mitmproxy#6270)

Author: mhils

release/docker/Dockerfile

@@ -8,7 +8,7 @@ FROM python:3.11-slim-bullseye
 
 RUN useradd -mU mitmproxy
 RUN apt-get update \
-    && apt-get install -y --no-install-recommends gosu \
+    && apt-get install -y --no-install-recommends gosu nano \
     && rm -rf /var/lib/apt/lists/*
 
 COPY --from=wheelbuilder /wheels /wheels