Only match SERVER_NAME subdomains when explicitly asked

This change has been introduced in Flask 3.1.0 and actually makes sense:
SERVER_NAME now matches subdomains when subdomain_matching is set. Let’s follow
the same rule for Flask-WeasyPrint.

flask_weasyprint/__init__.py

@@ -20,8 +20,9 @@ def make_flask_url_dispatcher():
     has returned.
 
     Dispatch to the context’s app URLs below the context’s root URL. If the
-    application has a ``SERVER_NAME`` :doc:`configuration <flask:config>`, also
-    accept URLs that have that domain name or a subdomain thereof.
+    application has a ``SERVER_NAME`` :doc:`configuration <flask:config>` and
+    ``subdomain_matching`` is set, also accept URLs that have that domain name
+    or a subdomain thereof.
 
     """
     def parse_netloc(netloc):
@@ -33,7 +34,7 @@ def parse_netloc(netloc):
     root_path = request.script_root
 
     server_name = app.config.get('SERVER_NAME')
-    if server_name:
+    if server_name and app.subdomain_matching:
         hostname, port = parse_netloc(server_name)
 
         def accept(url):

tests/test_flask_weasyprint.py

@@ -111,7 +111,7 @@ def add_redirect(old_url, new_url):
 
 
 def test_dispatcher():
-    app = Flask(__name__)
+    app = Flask(__name__, subdomain_matching=True)
     app.config['PROPAGATE_EXCEPTIONS'] = True
 
     @app.route('/')