Merge #1239: maintenance-table: update for 31.x release

1088d56 maintenance-table: update for 31.x release (fanquake)

Pull request description:

  Now that `31.0` is released:
  * Add placeholder for 32.x
  * Add `28.x` EOL date

ACKs for top commit:
  polespinasa:
    utACK 1088d56
  willcl-ark:
    ACK 1088d56
  hebasto:
    ACK 1088d56.
  darosior:
    utACK 1088d56

Tree-SHA512: 9aa86854164d596b77b82d6e87f272b96650a008f1ab3a105b4d28e398cf56c893b909b8a870e7fc6c6f7ac6d0be0ef1adccb3725922fb87e28c10272905a3c8

Author: fanquake

_includes/posts/maintenance-table.md

@@ -1,7 +1,8 @@
-| 31.x   | TBA*       | after v34.0  |
+| 32.x   | TBA*       | after v35.0  |
+| 31.x   | 2026-04-19 | after v34.0  |
 | 30.x   | 2025-10-10 | after v33.0  |
 | 29.x   | 2025-04-14 | after v32.0  |
-| 28.x   | 2024-10-02 | after v31.0  |
+| 28.x   | 2024-10-02 | 2026-04-19   |
 | 27.x   | 2024-04-16 | 2025-10-10   |
 | 26.x   | 2023-12-06 | 2025-04-14   |
 | 25.x   | 2023-05-18 | 2024-10-02   |