chore(config): upgrade to gosettings v0.4.0

- drop qdm12/govalid dependency
- upgrade qdm12/ss-server to v0.6.0
- do not unset sensitive config settings (makes no sense to me)

internal/configuration/settings/helpers.go

@@ -0,0 +1,5 @@
+package settings
+
+func ptrTo[T any](value T) *T {
+	return &value
+}