docs: fix four links to test files that moved in 2021

CONTRIBUTING.md

@@ -73,7 +73,7 @@ If testing from the root directory of this repo, create a new file (e.g. test.py
 
 The PR must pass all the tests before it is reviewed.
 
-All test files are in the [`test`](test) directory. For the purposes of contributing to this repo, please update the [`test_sendgrid.py`](test/test_sendgrid.py) file with unit tests as you modify the code.
+All test files are in the [`test`](test) directory. For the purposes of contributing to this repo, please update the [`test_sendgrid.py`](test/unit/test_sendgrid.py) file with unit tests as you modify the code.
 
 The integration tests require a Twilio SendGrid mock API in order to execute. We've simplified setting this up using Docker to run the tests. You will just need [Docker Desktop](https://docs.docker.com/get-docker/) and `make`.
 

TROUBLESHOOTING.md

@@ -124,7 +124,7 @@ Please review [our use_cases](use_cases/README.md) for examples of error handlin
 
 Twilio SendGrid's Event Webhook will notify a URL via HTTP POST with information about events that occur as your mail is processed. [This](https://docs.sendgrid.com/for-developers/tracking-events/getting-started-event-webhook-security-features) article covers all you need to know to secure the Event Webhook, allowing you to verify that incoming requests originate from Twilio SendGrid. The sendgrid-python library can help you verify these Signed Event Webhooks.
 
-You can find the usage example [here](examples/helpers/eventwebhook/eventwebhook_example.py) and the tests [here](test/test_eventwebhook.py). 
+You can find the usage example [here](examples/helpers/eventwebhook/eventwebhook_example.py) and the tests [here](test/unit/test_eventwebhook.py). 
 If you are still having trouble getting the validation to work, follow the following instructions:
 - Be sure to use the *raw* payload for validation
 - Be sure to include a trailing carriage return and newline in your payload

sendgrid/helpers/inbound/README.md

@@ -127,8 +127,8 @@ This module is used to send sample test data. It is useful for testing and devel
 
 Tests are located in the root of this project in the /test folder:
 
-- [test_config.py](../../../test/test_config.py)
-- [test_parse.py](../../../test/test_parse.py)
+- [test_config.py](../../../test/unit/test_config.py)
+- [test_parse.py](../../../test/unit/test_parse.py)
 
 Learn about testing this code [here](../../../CONTRIBUTING.md#testing).