Run CI against PG snapshots

[svenklemm]

Run CI against PG snapshots to discover potential issues with
upcoming PG releases earlier.

[codecov]

Codecov Report

Merging #3519 (d01a9a1) into master (f7eceba) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3519      +/-   ##
==========================================
- Coverage   90.70%   90.69%   -0.02%     
==========================================
  Files         212      212              
  Lines       36278    36278              
==========================================
- Hits        32906    32902       -4     
- Misses       3372     3376       +4     

Impacted Files	Coverage Δ
src/adts/bit_array_impl.h	97.27% <ø> (ø)
src/bgw/job.c	91.63% <ø> (ø)
src/bgw/launcher_interface.c	72.22% <ø> (ø)
src/bgw/scheduler.c	83.04% <ø> (ø)
src/bgw/timer.c	66.66% <ø> (ø)
src/bgw_policy/chunk_stats.c	80.00% <ø> (ø)
src/cache.c	89.78% <ø> (ø)
src/cache_invalidate.c	85.41% <ø> (ø)
src/catalog.c	84.61% <ø> (ø)
src/chunk.c	96.12% <ø> (ø)
... and 76 more

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[mfundul]

Shouldn't this be Build PostgreSQL ${{ matrix.pg }} ${{matrix.snapshot}} ${{ matrix.build_type }}?

And more importantly, shouldn't the cache above it include the snapshot otherwise it will conflict on the same key?

[svenklemm]

The key won't conflict since matrix.pg is either 12 or 13 for snapshots while it's exact version for non-snapshots e.g. 13.4
But i should probably disable cache entirely for snapshots.