Revert reverse dependency check on main branch of graphix-symbolic (#345)

This commit restores the reverse‑dependency check against the main
branch of `graphix-symbolic`. The check will become functional once the
following pull request is approved and merged:
TeamGraphix/graphix-symbolic#4

Author: thierry-martinez

noxfile.py

@@ -62,8 +62,6 @@ def tests_symbolic(session: Session) -> None:
     with TemporaryDirectory() as tmpdir, session.cd(tmpdir):
         # If you need a specific branch:
         # session.run("git", "clone", "-b", "branch-name", "https://github.com/TeamGraphix/graphix-symbolic")
-        # See https://github.com/TeamGraphix/graphix-symbolic/pull/4
-        session.run("git", "clone", "-b", "branch_selector", "https://github.com/thierry-martinez/graphix-symbolic")
-        # session.run("git", "clone", "https://github.com/TeamGraphix/graphix-symbolic")
+        session.run("git", "clone", "https://github.com/TeamGraphix/graphix-symbolic")
         with session.cd("graphix-symbolic"):
             session.run("pytest", "--doctest-modules")