fix: shift renovate schedules to 5-7 PM Saturday to align with cron

CronJob runs at 0/6/12/18h. Old 2-4 PM window never had a run
inside it, so Renovate never created PRs. Shift to 5-7 PM so the
18:00 run lands in the window. nixpkgs-qt staggered to 7-9 PM.

renovate.json

@@ -13,7 +13,7 @@
   "lockFileMaintenance": {
     "enabled": true,
     "schedule": [
-      "after 2pm and before 4pm on Saturday"
+      "after 5pm and before 7pm on Saturday"
     ]
   },
   "dependencyDashboard": true,
@@ -39,7 +39,7 @@
         "/^nix-darwin$/"
       ],
       "schedule": [
-        "after 2pm and before 4pm on Saturday"
+        "after 5pm and before 7pm on Saturday"
       ]
     },
     {
@@ -53,7 +53,7 @@
         "/home-manager-unstable/"
       ],
       "schedule": [
-        "after 2pm and before 4pm on Saturday"
+        "after 5pm and before 7pm on Saturday"
       ]
     },
     {
@@ -65,7 +65,7 @@
         "/nixpkgs-qt/"
       ],
       "schedule": [
-        "after 4pm and before 6pm on Saturday"
+        "after 7pm and before 9pm on Saturday"
       ]
     },
     {