Bump version to 0.5.0

This is the first release from the SurrealDB-owned fork. We're no
longer tracking upstream `tikv/client-rust` versions — the crate is
published as `surrealdb-tikv-client`, which already disambiguates
from upstream's `tikv-client`, so the `-surreal.N` suffix is dropped
in favour of plain semver.

0.5.0 also sorts unambiguously above upstream's 0.4.0 publish from
2026-02-07 (which kept the same vulnerable dep stack as 0.3.0).

Author: tobiemh

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "surrealdb-tikv-client"
-version = "0.4.0-surreal.1"
+version = "0.5.0"
 keywords = ["TiKV", "KV", "distributed-systems"]
 license = "Apache-2.0"
 authors = ["The TiKV Project Authors"]