Add a pool timeout to try to fix open File descriptor issue like deno (#2205)

Theres no pool technically but i saw this on Deno as well so we can try
this out.

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> [!IMPORTANT]
> Set pool parameters in `builder()` in `mod.rs` to prevent stalling,
inspired by similar issues in Deno and other projects.
> 
>   - **Behavior**:
> - In `builder()` in `mod.rs`, set `pool_max_idle_per_host(0)` and
`pool_idle_timeout(Duration::from_nanos(1))` to prevent stalling in
Python.
> - References issues in `reqwest`, `deno`, `hyper`, and
`azure-sdk-for-rust` for context.
>   - **Comments**:
> - Updated comments in `builder()` to explain the rationale for pool
settings and link to related issues.
> 
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Author: aaronvg

engine/baml-runtime/src/request/mod.rs

@@ -14,11 +14,14 @@ fn builder() -> reqwest::ClientBuilder {
                 .connect_timeout(Duration::from_secs(10))
                 .danger_accept_invalid_certs(danger_accept_invalid_certs)
                 .http2_keep_alive_interval(Some(Duration::from_secs(10)))
-                // We don't want to keep idle connections around due to sometimes
-                // causing a stall in the connection pool across FFI boundaries
+                // To prevent stalling in python, we set the pool to 0 and idle timeout to 0.
+                // See:
                 // https://github.com/seanmonstar/reqwest/issues/600
+                // https://github.com/denoland/deno/issues/28853
+                // https://github.com/hyperium/hyper/issues/2312
+                // https://github.com/Azure/azure-sdk-for-rust/pull/1550
                 .pool_max_idle_per_host(0)
-
+                .pool_idle_timeout(std::time::Duration::from_nanos(1))
         }
     }
 }