docs: Explain how to run tests in CONTRIBUTING.md

Signed-off-by: Abdur-Rahmaan Janhangeer <cryptolabour@gmail.com>
Co-authored-by: Matt Wozniski <godlygeek@gmail.com>

Author: Abdur-rahmaanJ

CONTRIBUTING.md

@@ -57,6 +57,21 @@ Changes should always include tests. If this is a bug fix it is a good idea to a
 first commit of the pull request and the changes to fix the issue in subsequent commits to make it
 easier to validate it.
 
+### Running tests before submitting pull request
+
+To run local tests, first install the test requirements:
+
+```shell
+python3 -m pip install --upgrade pip
+python3 -m pip install -e . --group test
+```
+
+Then, run the check:
+
+```shell
+make check
+```
+
 ## Pull requests
 
 ### Linting your code