Bump required version of libpmemobj

[igchor]

Since introducing flat_transactions, 1.9 is needed.

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This change is 

[lukaszstolarczuk]

Reviewed 2 of 2 files at r1.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @igchor)

[lukaszstolarczuk]

Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @igchor)

a discussion (no related file):
pls bump also PMDK_VERSION in gha.yml (Win build)

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[igchor]

Reviewable status: 2 of 3 files reviewed, 1 unresolved discussion (waiting on @lukaszstolarczuk)

a discussion (no related file):

Previously, lukaszstolarczuk (Łukasz Stolarczuk) wrote…

pls bump also PMDK_VERSION in gha.yml (Win build)

Done.

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[codecov]

Codecov Report

Merging #998 (12d4e60) into master (480c990) will increase coverage by 0.14%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #998      +/-   ##
==========================================
+ Coverage   95.72%   95.86%   +0.14%     
==========================================
  Files          48       48              
  Lines        6291     6291              
==========================================
+ Hits         6022     6031       +9     
+ Misses        269      260       -9     

Flag	Coverage Δ
tests_clang_debug_cpp17	95.45% <ø> (+0.24%)	⬆️
tests_gcc_debug	92.47% <ø> (+0.03%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...ude/libpmemobj++/container/concurrent_hash_map.hpp	94.21% <0.00%> (+0.88%)	⬆️

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[lukaszstolarczuk]

Reviewed 1 of 1 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @igchor)