feat: add varnish httpcache using kube-httpcache (#18)

* feat: add varnish httpcache using kube-httpcache

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Co-authored-by: github-actions <github-actions@github.com>

README.md

@@ -45,14 +45,7 @@ Each step need to be implemented with tests!
     - [ ] depend on ready/live backend (needed?)
     - [x] generic way to inject sidecars
 
-- [ ] Start Varnish
-    - [ ] deployment
-        - [ ] do not depend on backend/front end to be  up, but configure to deliver from cache if possible.
-    - [ ] service
-    - [ ] pdb
-    - [ ] lifecycle checks (readiness, liveness)
-    - [ ] generic way to inject sidecars
-    - find a way to purge caches. based on kitconcept varnish purger? needs evaluation
+- [x] Start Varnish (using kube-httcache)
 
 - [ ] Other Languages
     - [x] Check Python distribution