make sure Jest closes all open handles

.rtx.toml

@@ -0,0 +1,2 @@
+[tools]
+node = "18"

test/server/counterfact.test.js

@@ -134,5 +134,10 @@ describe("integration test", () => {
 
       await moduleLoader.stopWatching();
     });
+
+    // eslint-disable-next-line promise/avoid-new
+    await new Promise((resolve) => {
+      proxyTarget.close(resolve);
+    });
   });
 });

test/typescript-generator/specification.test.js

@@ -57,7 +57,10 @@ describe("a Specification", () => {
       hello: "world",
     });
 
-    await server.close();
+    // eslint-disable-next-line promise/avoid-new
+    await new Promise((resolve) => {
+      server.close(resolve);
+    });
   });
 
   it("returns a requirement for a URL", async () => {