Update build.rs

[opsmanager1]

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[opsmanager1]

This PR solve the issue

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/root/.nexus/network-api exists. Updating.
Saved working directory and index state WIP on (no branch): 6cdfb73 fix: proving bug fixes (#1367)
HEAD is now at 6cdfb73 fix: proving bug fixes (#1367)
Compiling nexus-vm-prover v0.2.3 (https://github.com/nexus-xyz/nexus-zkvm?branch=neo#ae4e2725)
Compiling nexus-network v0.5.3 (/root/.nexus/network-api/clients/cli)
Compiling tokio-tungstenite v0.23.1
Compiling sysinfo v0.33.1
Compiling prost v0.13.1
error: failed to run custom build command for nexus-network v0.5.3 (/root/.nexus/network-api/clients/cli)

Caused by:
process didn't exit successfully: /root/.nexus/network-api/clients/cli/target/release/build/nexus-network-8c54f0d68a838e59/build-script-build (exit status: 1)
--- stdout
cargo:rerun-if-changed=proto/orchestrator.proto
cargo:rerun-if-changed=build.rs
Current dir: "/root/.nexus/network-api/clients/cli"
Looking for proto file at: "/root/.nexus/network-api/clients/cli/proto/orchestrator.proto"
protoc is installed and accessible.
Output directory src/proto exists.
Error compiling protobuf files: protoc failed: orchestrator.proto: This file contains proto3 optional fields, but --experimental_allow_proto3_optional was not set.

Error: protoc failed: orchestrator.proto: This file contains proto3 optional fields, but --experimental_allow_proto3_optional was not set.

--- stderr
Error: Custom { kind: Other, error: "protoc failed: orchestrator.proto: This file contains proto3 optional fields, but --experimental_allow_proto3_optional was not set.\n" }
warning: build failed, waiting for other jobs to finish...