[IMP] supported_versions: release saas-18.4

closes #14036

X-original-commit: ce12bbe
Signed-off-by: Antoine Vandevenne (anv) <[email protected]>

Author: AntoineVDV

content/administration/supported_versions.rst

@@ -31,6 +31,12 @@ This matrix shows the support status of every version.
      - On-Premise
      - Release date
      - End of support
+   * - Odoo SaaS 18.4
+     - |green|
+     - N/A
+     - N/A
+     - July 2025
+     -
    * - Odoo SaaS 18.3
      - |green|
      - N/A