chore: update toolchain nightly-2026-06-20

fgdorais · fgdorais · commit 2a95a6385891 · 2026-06-20T10:02:20.000Z
diff --git a/lean-toolchain b/lean-toolchain
@@ -1 +1 @@
-leanprover/lean4:nightly-2026-06-18
+leanprover/lean4:nightly-2026-06-20
