rust-toolchain: use christmas nightly

Stan Drozd · Stan Drozd · commit 5130db479029 · 2023-01-03T18:29:56.000+01:00
diff --git a/rust-toolchain b/rust-toolchain
@@ -2,5 +2,5 @@
 # ci/rust-version.sh in the branch of the solana repo that corresponds
 # with the version we're using.
 [toolchain]
-channel = "1.63.0"
+channel = "nightly-2022-12-24"
 profile = "minimal"
