Added playwright information for debian

## Reference Issues/PRs

resolve #283

## What does this implement/fix?

- Added missing information (guide) on how to resolve dependencies which are required, in order to install `playwright` (which is required to run tests) on debian

CONTRIBUTING.md

@@ -1,6 +1,7 @@
 # Contribute to `vite-plugin-ssr`
 
 - [System requirements](#system-requirements)
+  - [Testing on Debian](#testing-on-debian)
 - [Install & build](#install--build)
 - [Ceate new example](#create-new-example)
 - [Modify existing example](#modify-existing-example)
@@ -17,6 +18,64 @@
 
 > These requirements are for developing only; `vite-plugin-ssr` can be used with any package manager, Windows, and Node.js `>= v12.19.0`.
 
+### Testing on Debian
+
+To run the test suite on Debian, additional dependencies are needed to install [playwright](https://github.com/microsoft/playwright).
+
+<details>
+  <summary>Click for details</summary>
+
+  #### Installing playwright
+
+  When running the test suite on Debian, playwright prompts to install its dependencies using:
+
+  ```shell
+  npx playwright install-deps
+  ```
+
+  According to the playwright's [system requirements](https://playwright.dev/docs/library#system-requirements), only Ubuntu is officially supported, so when running the command, it tries to install the required packages `libjpeg-turbo8` and `libicu66` with apt-get, which does not exist in the Debian sources list.
+
+  #### Resolve missing dependencies
+
+  To resolve the missing dependencies, you can:
+
+  1. either follow the error messages and install all dependencies manually
+  2. add `non-free` sources to `sources.list` and install `libjpeg-turbo8` and `libicu66` manually
+
+  To add the `non-free` sources to `deb` and `deb-src`:
+
+  ```shell
+  sudo nano /etc/apt/sources.list
+
+  # add the sources
+
+  deb http://deb.debian.org/debian/ bullseye main non-free
+  deb-src http://deb.debian.org/debian/ bullseye main non-free
+
+  # update package information
+
+  sudo apt-get update
+  ```
+
+  Download the official Ubuntu `libjpeg-turbo8` and `libicu66` packages from [pkgs.org](https://pkgs.org/) using `wget`:
+
+  - [libjpeg-turbo8](https://pkgs.org/download/libjpeg-turbo8)
+  - [libicu66](https://pkgs.org/download/libicu66)
+
+  You should be able to install both packages, since the required dependencies will be resolved automatically through the non-free sources:
+
+  ```shell
+  wget <url-topackage>.deb
+  dpkg -i <package>.deb
+  ```
+
+  With all packages successfully installed, you can finally install `playwright`:
+
+  ```shell
+  npx playwright install-deps
+  ``` 
+</details>
+
 <br/>
 
 ## Install & build