renovate.json: add regex for cypress docker image

Pin the browser versions with the digest, because updating them
with renovate did not work.

Author: BacLuc

docker-compose.yml

@@ -159,7 +159,7 @@ services:
       - FUNCTION_ENABLE_INCOGNITO_MODE=true
 
   e2e:
-    image: cypress/included:cypress-13.13.0-node-20.15.1-chrome-126.0.6478.114-1-ff-128.0-edge-126.0.2592.61-1@sha256:f9733a2cadc3aa270e40f8ce1158a23cb99703476a9db7154b4ecc51ba02bd5c
+    image: cypress/included:13.13.0@sha256:f9733a2cadc3aa270e40f8ce1158a23cb99703476a9db7154b4ecc51ba02bd5c
     profiles: ['e2e']
     container_name: 'ecamp3-e2e'
     environment: