Run "sudo apt update" before installing dependencies. (KhronosGroup#3474

)

Suggested on:
https://github.com/orgs/community/discussions/26649

as solution for failing Github action in:
https://github.com/KhronosGroup/WebGL/runs/7718272204?check_suite_focus=true

.github/workflows/lint.yml

@@ -24,6 +24,7 @@ jobs:
         python-version: 3.9
     - name: Install dependencies
       run: |
+        sudo apt update
         sudo apt-get install libxml2-utils
         python -m pip install --upgrade pip
         pip install --upgrade setuptools