find-kedro with src directory - improve error message

[WaylonWalker]

When using find-kedro in a project with a src directory the cli throws a really confusing error message. when specifying the directory it works just fine.

find-project on  main via 🐍 v3.8.5 via 🅒 kedro took 4s 
❯ find-kedro
Traceback (most recent call last):
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/pkg_resources/__init__.py", line 2191, in _handle_ns
    loader = importer.find_spec(packageName).loader
  File "<frozen importlib._bootstrap_external>", line 1466, in find_spec
  File "<frozen importlib._bootstrap_external>", line 64, in _path_join
  File "<frozen importlib._bootstrap_external>", line 64, in <listcomp>
AttributeError: 'PosixPath' object has no attribute 'rstrip'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/waylon/miniconda3/envs/kedro/bin/find-kedro", line 8, in <module>
    sys.exit(cli())
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/find_kedro/cli.py", line 85, in cli
    pipelines = find_kedro(
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/find_kedro/core.py", line 55, in find_kedro
    modules[key] = _import(nodes_file, directory)
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/find_kedro/core.py", line 250, in _import
    spec.loader.exec_module(module)
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "venv/lib/python3.8/site-packages/tables/nodes/filenode.py", line 41, in <module>
    import tables
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/tables/__init__.py", line 148, in <module>
    from .tests import print_versions, test
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/tables/tests/__init__.py", line 21, in <module>
    from tables.tests.common import print_versions
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/tables/tests/common.py", line 25, in <module>
    from pkg_resources import resource_filename
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3239, in <module>
    def _initialize_master_working_set():
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3222, in _call_aside
    f(*args, **kwargs)
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3264, in _initialize_master_working_set
    tuple(
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3265, in <genexpr>
    dist.activate(replace=False)
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/pkg_resources/__init__.py", line 2780, in activate
    declare_namespace(pkg)
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/pkg_resources/__init__.py", line 2279, in declare_namespace
    _handle_ns(packageName, path_item)
  File "/home/waylon/miniconda3/envs/kedro/lib/python3.8/site-packages/pkg_resources/__init__.py", line 2196, in _handle_ns
    loader = importer.find_module(packageName)
  File "<frozen importlib._bootstrap_external>", line 486, in _find_module_shim
  File "<frozen importlib._bootstrap_external>", line 1421, in find_loader
  File "<frozen importlib._bootstrap_external>", line 1466, in find_spec
  File "<frozen importlib._bootstrap_external>", line 64, in _path_join
  File "<frozen importlib._bootstrap_external>", line 64, in <listcomp>
AttributeError: 'PosixPath' object has no attribute 'rstrip'