fix: Allowing servers dropdown to change when oas3Actions.setSelectedServer is called (#6358)

ref: #6351

test/e2e-cypress/tests/bugs/6351.js

@@ -0,0 +1,13 @@
+// http://github.com/swagger-api/swagger-ui/issues/6351
+
+describe("#6351: Server dropdown should change when switched via oas3Actions.setSelectedServer", () => {
+  it("should show different selected server", () => {
+    cy.visit("/?url=/documents/bugs/6351.yaml")
+      .get("select")
+      .contains("http://testserver1.com")
+      .window()
+      .then(win => win.ui.oas3Actions.setSelectedServer("http://testserver2.com"))
+      .get("select")
+      .contains("http://testserver2.com")
+  })
+})