Upgrade Rust to 1.52.0 (#17096)

* Upgrade Rust to 1.52.0
update nightly_version to newly pushed docker image
fix clippy lint errors
1.52 comes with grcov 0.8.0, include this version to script

* upgrade to Rust 1.52.1

* disabling Serum from downstream projects until it is upgraded to Rust 1.52.1

sdk/src/packet.rs

@@ -72,6 +72,7 @@ impl fmt::Debug for Packet {
     }
 }
 
+#[allow(clippy::uninit_assumed_init)]
 impl Default for Packet {
     fn default() -> Packet {
         Packet {