chore: update toolchain v4.29.0-rc8

Author: fgdorais

lake-manifest.json

@@ -5,7 +5,7 @@
    "type": "git",
    "subDir": null,
    "scope": "",
-   "rev": "42d2b4ed2e0a4ff27297332b18ad8690814b2574",
+   "rev": "629254926fb54ef83d582bd41a0b9eb72b934015",
    "name": "UnicodeBasic",
    "manifestFile": "lake-manifest.json",
    "inputRev": "main",
@@ -15,7 +15,7 @@
    "type": "git",
    "subDir": null,
    "scope": "",
-   "rev": "46f6618b9942c1f67ebe3b8051163ddb8d8ff496",
+   "rev": "bce25af79ec73f5e63240d4399a4cd8a6a227fcb",
    "name": "batteries",
    "manifestFile": "lake-manifest.json",
    "inputRev": "main",

lean-toolchain

@@ -1 +1 @@
-leanprover/lean4:v4.29.0-rc8
+leanprover/lean4:v4.29.0-rc8