Pin tcp_rerouting build dependencies for Rust 1.65 MSRV compatibility

Pin proc-macro2 and quote in build-dependencies to versions compatible
with Rust 1.65 (the SDK's MSRV). Without these pins, cargo may select
newer versions (e.g., quote 1.0.42) that require Rust 1.68+, causing
CI builds to fail.

This follows best practices by explicitly pinning problematic transitive
dependencies rather than setting rust-version, which is not used by
other examples.

Signed-off-by: Christof Gerber <[email protected]>

Author: SiiiTschiii

examples/tcp_rerouting/Cargo.toml

@@ -6,6 +6,7 @@ authors = ["Proxy-Wasm contributors"]
 description = "Proxy-Wasm plugin example: TCP Rerouting based on source IP"
 license = "Apache-2.0"
 edition = "2021"
+rust-version = "1.65"
 
 [lib]
 crate-type = ["cdylib"]