indexer-alt: fix connection timeout

## Description

Using `stringify!(DEFAULT...)` doesn't work, because it stringifies the
constant name, not its contents. This change uses `const_str::format` to
do the same thing instead.

## Test plan

Run the indexer without supplying a connection timeout. Before this
change it would fail with a parse int error, because it tried to
interpret the string `DEFAULT_CONNECTION_TIMEOUT_SECS` as an integer.

crates/sui-indexer-alt/Cargo.toml

@@ -19,6 +19,7 @@ bb8 = "0.8.5"
 bcs.workspace = true
 chrono.workspace = true
 clap.workspace = true
+const-str = { workspace = true, features = ["proc"] }
 diesel = { workspace = true, features = ["chrono"] }
 diesel-async = { workspace = true, features = ["bb8", "postgres", "async-connection-wrapper"] }
 diesel_migrations.workspace = true

crates/sui-indexer-alt/src/db.rs

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 use anyhow::anyhow;
+use const_str::format as const_format;
 use diesel::migration::MigrationVersion;
 use diesel_async::async_connection_wrapper::AsyncConnectionWrapper;
 use diesel_async::{
@@ -38,7 +39,7 @@ pub struct DbConfig {
     /// Time spent waiting for a connection from the pool to become available.
     #[arg(
         long,
-        default_value = stringify!(DEFAULT_CONNECTION_TIMEOUT_SECS),
+        default_value = const_format!("{DEFAULT_CONNECTION_TIMEOUT_SECS}"),
         value_name = "SECONDS",
         value_parser = |s: &str| s.parse().map(Duration::from_secs)
     )]