fix "redefine builtin" lint error

slither/utils/function.py

@@ -9,6 +9,6 @@ def get_function_id(sig: str) -> int:
     Return:
         (int)
     """
-    hash = keccak.new(digest_bits=256)
+    digest = keccak.new(digest_bits=256)
-    hash.update(sig.encode("utf-8"))
+    digest.update(sig.encode("utf-8"))
-    return int("0x" + hash.hexdigest()[:8], 16)
+    return int("0x" + digest.hexdigest()[:8], 16)