chore: changeset for secure mode (#2459)

Changeset for the secure mode PR: #2404.

Author: kevin-dp

.changeset/hot-taxis-judge.md

@@ -0,0 +1,7 @@
+---
+"@core/sync-service": patch
+---
+
+Electric now runs in Secure mode by default, requiring an `ELECTRIC_SECRET` to be set.
+
+BREAKING CHANGE: Electric now needs to be started with an `ELECTRIC_SECRET` environment variable unless `ELECTRIC_INSECURE=true` is set.