Improve Dockerfile (#1962)

- add curl for HTTPS healthchecks (https://github.com/Kozea/Radicale/issues/1961)
- remove default TCP port EXPOSE command as it is not really usefull (https://forums.docker.com/t/what-is-the-use-of-expose-in-docker-file/37726)

Dockerfile

@@ -19,14 +19,12 @@ WORKDIR /app
 
 RUN addgroup -g 1000 radicale \
     && adduser radicale --home /var/lib/radicale --system --uid 1000 --disabled-password -G radicale \
-    && apk add --no-cache ca-certificates openssl
+    && apk add --no-cache ca-certificates openssl curl
 
 COPY --chown=radicale:radicale --from=builder /app/venv /app
 
 # Persistent storage for data
 VOLUME /var/lib/radicale
-# TCP port of Radicale
-EXPOSE 5232
 # Run Radicale
 ENTRYPOINT [ "/app/bin/python", "/app/bin/radicale"]
 CMD ["--hosts", "0.0.0.0:5232,[::]:5232"]