http2,test: mark test-http2-client-upload flaky on win32
Test recently started failing only in CI, unable to recreate locally on multiple test machines. Need to investigate further.
/cc @addaleax
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
commit message follows commit guidelines
Affected core subsystem(s)
http2, test