chore: support configurable Go module proxy

scripts/verifyLinux.py

@@ -24,6 +24,7 @@ def workspace_output(root: Path, value: str) -> tuple[Path, str]:
 def main() -> None:
     parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument("--image", default="golang:1.25", help="Docker image (default: golang:1.25)")
+    parser.add_argument("--goproxy", default="", help="optional Go module proxy passed to the container")
     parser.add_argument("--gomaxprocs", type=int, default=4)
     parser.add_argument("--load", action="store_true", help="also run the isolated server matrix")
     parser.add_argument("--tls", action="store_true", help="run the load matrix over TLS")
@@ -70,8 +71,10 @@ def main() -> None:
         "-w", "/workspace",
         "-e", "GOWORK=off",
         "-e", f"GOMAXPROCS={args.gomaxprocs}",
-        args.image, "sh", "-c", command,
     ]
+    if args.goproxy:
+        docker_args += ["-e", f"GOPROXY={args.goproxy}"]
+    docker_args += [args.image, "sh", "-c", command]
     print(f"Linux verification image: {args.image}", flush=True)
     print(f"Linux verification command: {command}", flush=True)
     result = subprocess.run(docker_args, cwd=root)