build: stop linking the removed zvec_proto from the utf8 acp tests

The Windows code-page tests added by "fix: handle UTF-8 paths
correctly on Windows" still list zvec_proto, which this branch no
longer builds, so MSVC failed with LNK1181: cannot open input file
'zvec_proto.lib'. No source under tests/db/utf8_acp uses protobuf.

Author: chinaux

tests/db/utf8_acp/CMakeLists.txt

@@ -9,7 +9,6 @@ endif()
 
 set(UTF8_ACP_LIBS
     zvec
-    zvec_proto
     core_knn_flat
     core_knn_flat_sparse
     core_knn_hnsw