chore: bump ruvector-postgres to 2.0.4 after SPARQL fixes (#180)

Published ruvector-postgres@2.0.4 to crates.io with SPARQL parser
backtrack fix, executor memory leak fix, and catch_unwind safety.

Co-Authored-By: claude-flow <ruv@ruv.net>

Author: ruvnet

crates/ruvector-postgres/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ruvector-postgres"
-version = "2.0.3"
+version = "2.0.4"
 edition = "2021"
 license = "MIT"
 description = "High-performance PostgreSQL vector database extension v2 - pgvector drop-in replacement with 230+ SQL functions, SIMD acceleration, Flash Attention, GNN layers, hybrid search, multi-tenancy, self-healing, and self-learning capabilities"