Remove --user flag for pip install in CI setup

Author: youtux

.github/workflows/main.yml

@@ -17,7 +17,7 @@ jobs:
         # We need a recent version of `packaging`, otherwise we encounter this bug:
         # https://github.com/pypa/twine/issues/1216
         run: |
-          python3 -m pip install --user build twine packaging>=25.0
+          python3 -m pip install build twine packaging>=25.0
           python3 -m pip freeze
       - name: Build a binary wheel and a source tarball
         run: python3 -m build