kubernetes: add missing BASE_HOST env var

kubernetes/backend-go-deployment.yaml

@@ -27,6 +27,8 @@ spec:
         env:
         - name: MODE
           value: release
+        - name: BASE_HOST
+          value: villas-new.k8s.fein-aachen.org
         - name: DB_NAME
           value: villas
         - name: DB_HOST