depends: bump libmultiprocess to fix capnproto deprecation warnings

This incorporates PR https://github.com/chaincodelabs/libmultiprocess/pull/88
"Fix current deprecation warnings as of capnproto-1.0.1" and reverts the
NO_WERROR CI workaround added in https://github.com/bitcoin/bitcoin/pull/28735

ci/test/00_setup_env_i686_multiprocess.sh

@@ -15,4 +15,3 @@ export GOAL="install"
 export BITCOIN_CONFIG="--enable-debug CC='clang -m32' CXX='clang++ -m32' \
 LDFLAGS='--rtlib=compiler-rt -lgcc_s' CPPFLAGS='-DBOOST_MULTI_INDEX_ENABLE_SAFE_MODE'"
 export TEST_RUNNER_ENV="BITCOIND=bitcoin-node"
-export NO_WERROR=1  # Temporary workaround to avoid -Wdeprecated-declarations from KJ