devpi-server: add py as runtime dep, add version test

the test is not performed in the postCheck phase because the dependency py was previously
provided as nativeTestInput. Running test in the installPhase ensure no extra
dependencies are used which are not available at runtime

fixes #286156

pkgs/development/tools/devpi-server/default.nix

@@ -20,6 +20,8 @@
 , strictyaml
 , waitress
 , webtest
+, testers
+, devpi-server
 }:
 
 
@@ -64,6 +66,7 @@ buildPythonApplication rec {
     setuptools
     strictyaml
     waitress
+    py
   ] ++ passlib.optional-dependencies.argon2;
 
   nativeCheckInputs = [
@@ -103,6 +106,10 @@ buildPythonApplication rec {
     "devpi_server"
   ];
 
+  passthru.tests.version = testers.testVersion {
+    package = devpi-server;
+  };
+
   meta = with lib;{
     homepage = "http://doc.devpi.net";
     description = "Github-style pypi index server and packaging meta tool";