Update alpine Docker tag to v3.18.4

#### 📖 Summary

- adds tzdate packaqge
- add TZ env

#### 📑 Test Plan

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- [x] CI pipeline tests
- [ ] Custom test
- [ ] No test plan

##### Details / Justification

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#### 📚 Additional Notes

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Reviewed-on: #14

Dockerfile

@@ -29,11 +29,12 @@ ENV LOGLEVEL "Info"
 ENV MAXCLIENTS "600"
 ENV FILTER_FILE "/app/filter"
 
+ENV TZ "Europe/Berlin"
 
 # get existing packages
 # curl for healthchecks and debugging
 RUN apk add --no-cache \
-      tinyproxy curl
+      tinyproxy curl tzdata
 
 COPY entrypoint.sh /app/entrypoint.sh