test: skip test.yml in PRs (#8330)

.github/workflows/test.yml

@@ -1,7 +1,6 @@
 name: Tests
 
 on:
-  pull_request:
   push:
     branches: master
 

packages/excalidraw/tests/MermaidToExcalidraw.test.tsx

@@ -90,7 +90,7 @@ describe("Test <MermaidToExcalidraw/>", () => {
 
   it("should open mermaid popup when active tool is mermaid", async () => {
     const dialog = document.querySelector(".ttd-dialog")!;
-    await waitFor(() => dialog.querySelector("canvas"));
+    await waitFor(() => expect(dialog.querySelector("canvas")).not.toBeNull());
     expect(dialog.outerHTML).toMatchSnapshot();
   });