verdi run: Do not add pathlib.Path instance to sys.path (#5810)

The `verdi run` command updates `sys.path` to include the current
working directory such that modules in it can be imported by the script
being run. However, it was using `pathlib` to get the CWD and was adding
a `Path` instance to the path, which should only contain `str`
instances. This was uncovered by trying to import `tensorflow` which
also manipulates the `sys.path` and was raising an error since it was
trying to iterate over all elements and `pathlib.Path` is not iterable,
unlike `str`.

.pre-commit-config.yaml

@@ -90,7 +90,6 @@ repos:
                 aiida/cmdline/commands/cmd_devel.py|
                 aiida/cmdline/commands/cmd_group.py|
                 aiida/cmdline/commands/cmd_node.py|
-                aiida/cmdline/commands/cmd_run.py|
                 aiida/cmdline/commands/cmd_shell.py|
                 aiida/cmdline/commands/cmd_storage.py|
                 aiida/cmdline/groups/dynamic.py|

aiida/cmdline/commands/cmd_run.py

@@ -28,7 +28,7 @@ def update_environment(argv):
         _argv = sys.argv[:]
 
         # Add the current working directory to the path, such that local modules can be imported
-        sys.path.append(pathlib.Path.cwd().resolve())
+        sys.path.append(str(pathlib.Path.cwd().resolve()))
         sys.argv = argv[:]
         yield
     finally: