Update protobuf dependency to the version that fixes memory leaks.

[tvalentyn]

Update protobuf version to a newer version that fixes some memory leaks.

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[chleech]

LFG

[codecov]

Codecov Report

Merging #28365 (0335981) into master (7ba4fa9) will decrease coverage by 0.03%.
Report is 44 commits behind head on master.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #28365      +/-   ##
==========================================
- Coverage   72.36%   72.33%   -0.03%     
==========================================
  Files         681      681              
  Lines      100364   100364              
==========================================
- Hits        72624    72598      -26     
- Misses      26165    26192      +27     
+ Partials     1575     1574       -1     

Flag	Coverage Δ
python	82.90% <ø> (-0.02%)	⬇️

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Files Changed	Coverage Δ
sdks/python/setup.py	0.00% <ø> (ø)

... and 13 files with indirect coverage changes

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[damccorm]

LGTM

[tvalentyn]

Unfrotunately most recent version of protbuf is still leaking memory, will follow up with protobuf team.

[tvalentyn]

It might not fix #28246 yet but we should still upgrade since this version fixes two other known issues: protocolbuffers/protobuf#10088, https://github.com/protocolbuffers/upb/issues/1243 .