Automated update to Github CI to rustc nightly-2025-06-20

Update Nightly Rustc Bot · Update Nightly Rustc Bot · commit 6d75a3f0a571 · 2025-06-21T02:08:42.000Z
diff --git a/nightly-version b/nightly-version
@@ -1 +1 @@
-nightly-2025-03-21
+nightly-2025-06-20
