CONTRIBUTING: fix 404 link (#4479)

Author: xrmx

CONTRIBUTING.md

@@ -294,7 +294,7 @@ Some of the tox targets install packages from the [OpenTelemetry Python Core Rep
 CORE_REPO_SHA=c49ad57bfe35cfc69bfa863d74058ca9bec55fc3 tox
 ```
 
-The continuous integration overrides that environment variable with as per the configuration [here](https://github.com/open-telemetry/opentelemetry-python-contrib/blob/main/.github/workflows/test_0.yml#L14).
+The continuous integration overrides that environment variable with as per the configuration [here](https://github.com/open-telemetry/opentelemetry-python-contrib/blob/main/.github/workflows/test.yml#L17).
 
 ## Style Guide