Update TOC.yml

Removing a duplicated page

Author: kabharati

articles/postgresql/TOC.yml

@@ -486,8 +486,6 @@
       href: flexible-server/concepts-security.md
     - name: Azure AD Authentication
       href: flexible-server/concepts-azure-ad-authentication.md
-    - name: Major Version Upgrade
-      href: flexible-server/concepts-major-version-upgrade.md
     - name: Compliance
       href: flexible-server/concepts-compliance.md
     - name: Limits