fix(clean): erase venvs folder after all the venvs packages were deleted

Author: ever3001

src/pipx/commands/clean_cmd.py

@@ -163,6 +163,8 @@ def _venvs_cleanup(verbose: bool) -> ExitCode:
         for package_name, error in failed:
             print(f"  - {package_name}: {error}")
         return EXIT_CODE_VENVS_CLEANUP_FAIL
+    
+    rmdir(ctx.venvs, safe_rm=True)
 
     print(f"{stars} All installed packages removed.")
     return EXIT_CODE_OK