[python] Add back __enter__ and __exit__ methods for non asyncio (#16979)

modules/openapi-generator/src/main/resources/python/api_client.mustache

@@ -92,6 +92,13 @@ class ApiClient:
     async def close(self):
         await self.rest_client.close()
 {{/asyncio}}
+{{^asyncio}}
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        pass
+{{/asyncio}}
 
     @property
     def user_agent(self):

samples/client/echo_api/python-disallowAdditionalPropertiesIfNotPresent-true/openapi_client/api_client.py

@@ -90,6 +90,11 @@ class ApiClient:
         self.user_agent = 'OpenAPI-Generator/1.0.0/python'
         self.client_side_validation = configuration.client_side_validation
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        pass
 
     @property
     def user_agent(self):

samples/client/echo_api/python/openapi_client/api_client.py

@@ -90,6 +90,11 @@ class ApiClient:
         self.user_agent = 'OpenAPI-Generator/1.0.0/python'
         self.client_side_validation = configuration.client_side_validation
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        pass
 
     @property
     def user_agent(self):

samples/openapi3/client/petstore/python/petstore_api/api_client.py

@@ -89,6 +89,11 @@ class ApiClient:
         self.user_agent = 'OpenAPI-Generator/1.0.0/python'
         self.client_side_validation = configuration.client_side_validation
 
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        pass
 
     @property
     def user_agent(self):