flake.lock: Update

Flake lock file updates:

• Updated input 'circt-src':
    'github:llvm/circt/6dcdb59ce1e82dc6c7878c670dabf5299093f774' (2024-08-29)
  → 'github:llvm/circt/1c5dfa4a27731428dccd91ca94169455bd7511ac' (2024-09-03)
• Updated input 'llvm-submodule-src':
    'github:llvm/llvm-project/c69b8c445a6b7efd29e67b665adaf04575f3ed92' (2024-08-09)
  → 'github:llvm/llvm-project/a527248a3c2d638b0c92a06992f3f1c1f80842ad' (2024-08-30)
• Updated input 'slang-src':
    'github:MikePopoloski/slang/4bffca04fe8c48b42ad08e0ceb8160cd317d97f0' (2024-08-29)
  → 'github:MikePopoloski/slang/0ef0ac467cbd0ca11baf91398f8699bd96bcf4ff' (2024-08-29)