[SKiDL BUG] search_footprints results in `FileNotFoundError: [Errno 2] No such file or directory:`

[blark]

Describe the bug Search footprints, with a properly configured path doesn't work - resulting in an exception, seemingly due to improper parsing of the path in footprint_search_paths (running on macOS)

To Reproduce Steps to reproduce the behavior:

1. set footprint_search_paths['kicad8'] = '/Applications/KiCad/KiCad.app/Contents/SharedSupport/footprints/'
2. search_footprints('cap')
3. FileNotFoundError: [Errno 2] No such file or directory: 'A'

Expected behavior Return a list of footprints matching "cap"

Desktop (please complete the following information):

• OS macOS 14.5
• Python version 3.12.3
• SKiDL version [e.g. 22] 1.2.3

---------------------------------------------------------------------------
FileNotFoundError                         Traceback (most recent call last)
Cell In[18], line 2
      1 footprint_search_paths['kicad8'] = '/Applications/KiCad/KiCad.app/Contents/SharedSupport/footprints/'
----> 2 search_footprints('cap')

File /opt/homebrew/lib/python3.11/site-packages/skidl/part_query.py:379, in search_footprints(terms, tool)
    374 """
    375 Print a list of footprints with the regex term within their description/tags.
    376 """
    378 footprints = []
--> 379 for fp in search_footprints_iter(terms, tool):
    380     if fp[0] == "LIB":
    381         print(" " * 79, "\rSearching {} ...".format(fp[1]), sep="", end="\r")

File /opt/homebrew/lib/python3.11/site-packages/skidl/part_query.py:304, in search_footprints_iter(terms, tool)
    302     footprint_cache.clear()
    303     for path in skidl.footprint_search_paths[tool]:
--> 304         footprint_cache.load(path)
    306 # Get the number of footprint libraries to be searched..
    307 num_fp_libs = len(footprint_cache)

File /opt/homebrew/lib/python3.11/site-packages/skidl/part_query.py:268, in FootprintCache.load(self, path)
    263     continue
    265 # Get a list of all the footprint module files in the top-level of the library URI.
    266 filenames = [
    267     fn
--> 268     for fn in os.listdir(uri)
    269     if os.path.isfile(os.path.join(uri, fn))
    270     and fn.lower().endswith(".kicad_mod")
    271 ]
    273 # Create an entry in the cache for this nickname. (This will overwrite
    274 # any previous nickname entry, so make sure to scan fp-lib-tables in order of
    275 # increasing priority.) Each entry contains the path to the directory containing
    276 # the footprint module and a dictionary of the modules keyed by the module name
    277 # with an associated value containing the module file contents (which starts off
    278 # as None).
    279 self[nickname] = {
    280     "path": uri,
    281     "modules": {os.path.splitext(fn)[0]: None for fn in filenames},
    282 }

FileNotFoundError: [Errno 2] No such file or directory: 'A'