Add OS dependencies for run-test-server to DEPDENCIES.md

DEPENDENCIES.md

@@ -31,5 +31,19 @@
   editor plugins. Please refer to the `package.json` within
   `libs/ckeditor...zip` for a full list of said plugins.
 
-## For testing
+## For unit testing
 * qunit-2.9.2
+
+### Debian 12 (also on WSL)
+* unzip
+* gettext
+* firefox-esr
+* xvfb
+* libpci-dev
+* libegl1
+* imagemagick (to use `convert` on `screenshot.xwd`)
+
+Install test dependencies on Debian
+```bash
+sudo apt install unzip gettext firefox-esr xvfb x11-apps libpci-dev libegl1 imagemagick
+```