fix(cypress): fix typecheck

Part-of: <https://dev.funkwhale.audio/funkwhale/funkwhale/-/merge_requests/1795>

front/cypress/cypress.d.ts

@@ -1,7 +1,9 @@
-declare global {
-  namespace Cypress {
-    interface Chainable {
-      login(): Chainable<JQuery<HTMLElement>>
+declare module 'cypress' {
+  global {
+    namespace Cypress {
+      interface Chainable {
+        login(): Chainable<JQuery<HTMLElement>>
+      }
     }
   }
 }