Run docs on ubuntu (#455)

Author: blink1073

.github/workflows/tests.yml

@@ -66,7 +66,7 @@ jobs:
           pipx run doc8 --max-line-length=200
 
   docs:
-    runs-on: windows-latest
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
       - uses: jupyterlab/maintainer-tools/.github/actions/base-setup@v1