[skip ci] Update Contribution.md (#5352)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Shinji Watanabe <sw005320@gmail.com>

CONTRIBUTING.md

@@ -176,6 +176,45 @@ cd egs/mini_an4/your_task
 - [.github/workflows](.github/workflows/) configures Github Actions (unittests, integration tests).
 - [codecov.yml](codecov.yml) configures CodeCov (code coverage).
 
+### 5.2 Integration testing Locally (Github Actions locally)
+
+You can test if your PR complies with the integrations test before pushing a new update using [act](https://github.com/nektos/act).
+
+### 5.2.1 Installation
+
+To execute **act**:
+
+1. You first need to install [Docker](https://docs.docker.com/engine/install/) on your local PC. Do not forget to login into docker using `docker login`.
+
+2. Install Github CLI. The [instructions](https://github.com/cli/cli#installation) will change depending on your OS. For Linux, you can use the official sources to install the corresponding [package](https://github.com/cli/cli/blob/trunk/docs/install_linux.md#official-sources).
+
+3. Finally, install **act** through [package managers](https://github.com/nektos/act#installation-through-package-managers) or using the [Github CLI](https://github.com/nektos/act#installation-as-github-cli-extension). For Linux, you can use the command: `gh extension install https://github.com/nektos/gh-act`
+
+### 5.2.2 Usage
+
+In a command console:
+
+```bash
+cd <root_dir_espnet_clone>  # go to the root directory of your clone
+gh act
+```
+
+The program will start running all the CI tests that will run in the GitHub Action server.
+
+For specific jobs/workflow, you can use:
+
+```bash
+# For jobs:
+gh act -j <jobID>  # Where jobID is a string.
+
+# For workflows:
+gh act -W <workflowID>
+gh act -W .github/workflows/<filename>.yml
+```
+
+List the available jobID/workflowID with: `gh act -l`.
+You can get the list of workflow files from `ls .github/workflows`.
+
 ## 6 Writing new tools
 
 You can place your new tools under