[Python SDK] change library for sync client: httpX -> requests (aptos-labs#9038)

### Description

Observed two issues in httpX using the sync client, both related to latency:
(1) It does not properly reuse connections on POST, incurring the full TLS handshake time ~100ms.
(2) It seems to delay ~100ms sending of the POST body.

Combined, this was showing ~200ms additional time when measuring latency. These problems don't show up with requests.

Updated with `poetry lock` as well.

### Test Plan

Run `poetry install` `poetry install --sync` `make test` and `make examples`.
Also confirmed manually that latency is reduced when running an e2e measurement script.

Author: bchocho

ecosystem/python/sdk/CHANGELOG.md

@@ -4,6 +4,9 @@ All notable changes to the Aptos Python SDK will be captured in this file. This
 
 **Note:** Until we cut a 1.0.0 release, the Aptos Python SDK does not follow semantic versioning.
 
+## 0.6.3
+- Change sync client library from httpX to requests due to latency concerns.
+
 ## 0.6.2
 - Added custom header "x-aptos-client" to both sync/async RestClient
 

ecosystem/python/sdk/aptos_sdk/client.py

@@ -4,7 +4,7 @@
 import time
 from typing import Any, Dict, List
 
-import httpx
+import requests
 
 from . import ed25519
 from .account import Account
@@ -38,14 +38,16 @@ class RestClient:
     """A wrapper around the Aptos-core Rest API"""
 
     chain_id: int
-    client: httpx.Client
+    client: requests.Session
     client_config: ClientConfig
     base_url: str
 
     def __init__(self, base_url: str, client_config: ClientConfig = ClientConfig()):
         self.base_url = base_url
-        self.client = httpx.Client()
-        self.client.headers[Metadata.APTOS_HEADER] = Metadata.get_aptos_header_val()
+        self.client = requests.Session()
+        self.client.headers.update(
+            {Metadata.APTOS_HEADER: Metadata.get_aptos_header_val()}
+        )
         self.client_config = client_config
         self.chain_id = int(self.info()["chain_id"])
 
@@ -205,8 +207,8 @@ def simulate_transaction(
         headers = {"Content-Type": "application/x.aptos.signed_transaction+bcs"}
         response = self.client.post(
             f"{self.base_url}/transactions/simulate",
+            data=signed_transaction.bytes(),
             headers=headers,
-            content=signed_transaction.bytes(),
         )
         if response.status_code >= 400:
             raise ApiError(response.text, response.status_code)
@@ -217,8 +219,8 @@ def submit_bcs_transaction(self, signed_transaction: SignedTransaction) -> str:
         headers = {"Content-Type": "application/x.aptos.signed_transaction+bcs"}
         response = self.client.post(
             f"{self.base_url}/transactions",
+            data=signed_transaction.bytes(),
             headers=headers,
-            content=signed_transaction.bytes(),
         )
         if response.status_code >= 400:
             raise ApiError(response.text, response.status_code)