common: start PMem tests at 6:00 pm to get results early next day

PMem tests required about 14h30m for execution.
With execution started at noon results are practically available
at the end of working day.

Signed-off-by: Tomasz Gromadzki <tomasz.gromadzki@intel.com>

.github/workflows/pmem_tests.yml

@@ -6,8 +6,8 @@ name: PMEM tests
 on:
   workflow_dispatch:
   schedule:
-    # run this job at 00:00 UTC every day
-    - cron:  '0 0 * * *'
+    # run this job at 18:00 UTC every day
+    - cron:  '0 18 * * *'
 
 jobs:
   # Test the default build with the basic test suite.