goproxy: add goproxy to AppManager and use it in CI via flake.nix

Change-Id: I489d202c34219434653cfe3afbb19937dadd204e
diff --git a/charts/goproxy/Chart.yaml b/charts/goproxy/Chart.yaml
new file mode 100644
index 0000000..4eb5f60
--- /dev/null
+++ b/charts/goproxy/Chart.yaml
@@ -0,0 +1,6 @@
+apiVersion: v2
+name: goproxy
+description: A Helm chart for goproxy
+type: application
+version: 0.0.1
+appVersion: "0.0.1"