Ensure TCP connections are properly closed

Use a context-managed `requests.Session` to guarantee that the session and its underlying TCP connections are properly closed.
This prevents `ResourceWarning` messages being written to stderr.

Signed-off-by: Moritz Duchêne <debakel@users.noreply.github.com>

Author: Debakel

CHANGELOG.md

@@ -4,6 +4,8 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
+### Fixed
+- Ensure `requests.Session` is closed to prevent lingering TCP connections.
 
 ## [0.4.0] - 2025-01-20
 ### Changed

src/zapv2/__init__.py

@@ -137,12 +137,6 @@ def __init__(self, proxies=None, apikey=None, validate_status_code=False):
         # not very nice, but prevents warnings when accessing the ZAP API via https
         requests.packages.urllib3.disable_warnings(InsecureRequestWarning)
 
-        # Currently create a new session for each request to prevent request failing
-        # e.g. when polling the spider status
-        #self.session = requests.Session()
-        #if apikey is not None:
-        #  self.session.headers['X-ZAP-API-Key'] = apikey
-
     def urlopen(self, url, *args, **kwargs):
         """
         Opens a url forcing the proxies to be used.
@@ -170,11 +164,11 @@ def _request_api(self, url, query=None, method="GET", body=None):
 
         # In theory we should be able to reuse the session,
         # but there have been problems with that
-        self.session = requests.Session()
-        if self.__apikey is not None:
-          self.session.headers['X-ZAP-API-Key'] = self.__apikey
+        with requests.Session() as session:
+            if self.__apikey is not None:
+              session.headers['X-ZAP-API-Key'] = self.__apikey
 
-        response = self.session.request(method, url, params=query, data=body, proxies=self.__proxies, verify=False)
+            response = session.request(method, url, params=query, data=body, proxies=self.__proxies, verify=False)
 
         if (self.__validate_status_code and response.status_code >= 300 and response.status_code < 500):
             raise Exception("Non-successful status code returned from ZAP, which indicates a bad request: "