Downgrade testing dependency whatwg-url

Apparently in version 8.3.0 the implementation for whatwg-url changed
which breaks our test. We probably should deal with this in a follow-up.

yarn.lock

@@ -12695,13 +12695,13 @@ whatwg-mimetype@^2.3.0:
   integrity sha512-M4yMwr6mAnQz76TbJm914+gPpB/nCwvZbJU28cUD6dR004SAxDLOOSUaB1JDRqLtaOV/vi0IC5lEAGFgrjGv/g==
 
 whatwg-url@^8.0.0:
-  version "8.3.0"
-  resolved "https://registry.yarnpkg.com/whatwg-url/-/whatwg-url-8.3.0.tgz#d1e11e565334486cdb280d3101b9c3fd1c867582"
-  integrity sha512-BQRf/ej5Rp3+n7k0grQXZj9a1cHtsp4lqj01p59xBWFKdezR8sO37XnpafwNqiFac/v2Il12EIMjX/Y4VZtT8Q==
+  version "8.1.0"
+  resolved "https://registry.yarnpkg.com/whatwg-url/-/whatwg-url-8.1.0.tgz#c628acdcf45b82274ce7281ee31dd3c839791771"
+  integrity sha512-vEIkwNi9Hqt4TV9RdnaBPNt+E2Sgmo3gePebCRgZ1R7g6d23+53zCTnuB0amKI4AXq6VM8jj2DUAa0S1vjJxkw==
   dependencies:
     lodash.sortby "^4.7.0"
     tr46 "^2.0.2"
-    webidl-conversions "^6.1.0"
+    webidl-conversions "^5.0.0"
 
 which-module@^2.0.0:
   version "2.0.0"