Automated update to Github CI to rustc nightly-2025-08-15

Update Nightly Rustc Bot · Update Nightly Rustc Bot · commit f18a3683933e · 2025-08-16T02:08:34.000Z
diff --git a/nightly-version b/nightly-version
@@ -1 +1 @@
-nightly-2025-03-21
+nightly-2025-08-15
