flake.lock: Update

Flake lock file updates:

• Updated input 'circt-src':
    'github:llvm/circt/93228028868d539997d72947e53842b602c61824' (2024-09-26)
  → 'github:llvm/circt/e66d68089b46fea5d89c73fdbc15e8e48c63ffce' (2024-09-30)
• Updated input 'llvm-submodule-src':
    'github:llvm/llvm-project/da1a222337681c1823e9d6215451f392131ad8d1' (2024-09-19)
  → 'github:llvm/llvm-project/a285ba7529feaa7c49890e314facb5e9f4d8dc11' (2024-09-26)
• Updated input 'slang-src':
    'github:MikePopoloski/slang/6ad50f1d8cce84bbfc69696f29608cd997e43bc2' (2024-09-26)
  → 'github:MikePopoloski/slang/1fead9a9a9cd1a689c39234cdaafb554bb5627c3' (2024-09-28)