Fix query for certain postgresql versions.

Dependencies

• [2] KJQWSRCC Speed up hydra-update-gc-roots
• [3] 4X6NS66Q * Keep the most recent builds for each job.
• [4] IN272KZW * Automatically keep all builds in the latest successful release in
• [*] WZ3AEJ67 * hydra_update_gc_roots.pl registers build outputs that should be kept

Change contents

• replacement in src/script/hydra-update-gc-roots at line 97
  [2.2036]→[2.2036:2140](∅→∅)
  − " , 0) nth from builds b where project = ? and jobset = ? and isCurrent = 1) x " .
  [2.2036]

  [2.2140]
  + " , 0) as nth from builds b where project = ? and jobset = ? and isCurrent = 1) x " .