temp: make site-packages unwritable

Author: nedbat

.github/workflows/testsuite.yml

@@ -132,6 +132,7 @@ jobs:
           # For extreme debugging:
           python -c "import urllib.request as r; exec(r.urlopen('https://bit.ly/pydoctor').read())"
           env | sort
+          chmod u-w $(python -c "import site; print(site.getsitepackages()[0])")
 
       - name: "Install dependencies"
         run: |