[Panther] Configure env PANTHER_DEVTOOLS=0

Following symfony/panther#675 and symfony/ux#2873, passing `PANTHER_DEVTOOLS=0` (it is enabled by default) fixes issues when using Chrome 137+.

I agree this is not the best fix, surely something must be fixed upsteam, but for the moment, disabling devtools allows Panther to be usable again in some behaviors.

Author: Kocal

symfony/panther/1.0/manifest.json

@@ -21,7 +21,8 @@
     "dotenv": {
         "test": {
             "PANTHER_APP_ENV": "panther",
-            "PANTHER_ERROR_SCREENSHOT_DIR": "./var/error-screenshots"
+            "PANTHER_ERROR_SCREENSHOT_DIR": "./var/error-screenshots",
+            "PANTHER_DEVTOOLS": "0"
         }
     },
     "add-lines": [