ci: add nixtest job

flake.nix

@@ -141,7 +141,7 @@
         };
         # should set the "default" pipeline
         ci = {
-          stages = ["test" "build" "deploy"];
+          stages = ["test" "nixtest" "build" "deploy"];
           jobs = {
             "test" = {
               stage = "test";
@@ -197,6 +197,18 @@
                 }
               ];
             };
+            "nixtest" = {
+              stage = "nixtest";
+              script = [
+                # sh
+                "nix run .#nixtests:run -- --junit=junit.xml"
+              ];
+              allow_failure = true;
+              artifacts = {
+                when = "always";
+                reports.junit = "junit.xml";
+              };
+            };
           };
         };
         pipelines."non-default" = {