Update to docker 1.56.1

Author: ghaith

linux/Dockerfile

@@ -1,4 +1,4 @@
-FROM rust:1.56-bullseye
+FROM rust:1.56.1-bullseye
 
 # Fixed rust version to 12
 ARG LLVM_VER=12

win/Dockerfile

@@ -1,7 +1,7 @@
 FROM mcr.microsoft.com/windows/servercore:ltsc2019
 
 ARG LLVM_VER=12.0.1
-ARG RUST_VER=1.56.0
+ARG RUST_VER=1.56.1
 
 # Install VC++