Make the max redis pool size configurable via env var.

src/client_manager.rs

@@ -14,8 +14,13 @@ fn pool_from_redisinfo(info: &TrackerRedisInfo) -> color_eyre::Result<Pool<Clien
     };
     let new_client = Client::open(url)?;
 
+    let max_pool_size = std::env::var("MAX_REDIS_POOL_SIZE")
+        .unwrap_or_else(|| "32".to_string())
+        .parse()
+        .unwrap_or(32);
+
     let pool = Pool::builder()
-        .max_size(32)
+        .max_size(max_pool_size)
         .build(new_client)?;
     Ok(pool)
 }