Fixed an issue with mounting a parcel when StrictMode is enabled (#206)

* Fixed an issue with mounting a parcel when StrictMode is enabled

* Added changeset

* Run parcel test with and without strict mode enabled

* Properly setup the configuration of the react strict mode in th tests

.changeset/nasty-gifts-check.md

@@ -0,0 +1,5 @@
+---
+"single-spa-react": patch
+---
+
+Fixed an issue with mounting a parcel when StrictMode is enabled

package.json

@@ -90,7 +90,7 @@
     "@rollup/plugin-commonjs": "^20.0.0",
     "@rollup/plugin-node-resolve": "^13.0.4",
     "@testing-library/jest-dom": "^5.14.1",
-    "@testing-library/react": "^13.1.1",
+    "@testing-library/react": "^14.2.0",
     "@types/react": "^18.0.0",
     "@types/react-dom": "^18.0.0",
     "auto": "^10.37.6",