Replace REL_17_BETA2 with REL_17_STABLE in CI

[artemgavrilov]

https://www.postgresql.org/about/news/postgresql-164-158-1413-1316-1220-and-17-beta-3-released-2910/

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 84.88%. Comparing base (0c50b23) to head (127f22f). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #483 +/- ## ========================================== + Coverage 84.87% 84.88% +0.01% ========================================== Files 3 3 Lines 1296 1297 +1 Branches 198 198 ========================================== + Hits 1100 1101 +1 Misses 98 98 Partials 98 98 ```

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