Allow comments and empty lines in dictionary

[vries]

I'd like to add a comment to a dictionary (similar to how issue #2063 requests this for ignore-words files):

 gdbsever->gdbserver
 tcllint->tclint
 recordered->recorded
+# Comment.

but it makes codespell crash:

Traceback (most recent call last):
  File "/home/vries/.cache/pre-commit/repoxmktmlyg/py_env-python3.13/bin/codespell", line 6, in <module>
    sys.exit(_script_main())
             ~~~~~~~~~~~~^^
  File "/home/vries/.cache/pre-commit/repoxmktmlyg/py_env-python3.13/lib/python3.13/site-packages/codespell_lib/_codespell.py", line 1234, in _script_main
    return main(*sys.argv[1:])
  File "/home/vries/.cache/pre-commit/repoxmktmlyg/py_env-python3.13/lib/python3.13/site-packages/codespell_lib/_codespell.py", line 1363, in main
    build_dict(dictionary, misspellings, ignore_words)
    ~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/vries/.cache/pre-commit/repoxmktmlyg/py_env-python3.13/lib/python3.13/site-packages/codespell_lib/_spellchecker.py", line 57, in build_dict
    [key, data] = line.split("->")
    ^^^^^^^^^^^
ValueError: not enough values to unpack (expected 2, got 1)

Likewise, empty lines:

 gdbsever->gdbserver
 tcllint->tclint
+
 recordered->recorded

make codespell crash.

For now, for adding comments I'm making do with this hack:

 gdbsever->gdbserver
 tcllint->tclint
 recordered->recorded
+-># Comment.

[AlightSoulmate]

Add validation to build_dict loop in codespell_lib/_spellchecker.py to prevent crashes:

for line in f:
    # check empty lines and comments
    line = line.strip()
    if not line or line.startswith("#") or "->" not in line:
        continue
    [key, data] = line.split("->")