Use unstable rust-analyzer

Fixes proc-macro version mismatch

config.nix

@@ -1,4 +1,4 @@
-{ pkgs, inputs, ... }:
+{ pkgs, pkgs-unstable, inputs, ... }:
 {
   colorschemes.tokyonight.enable = true;
 
@@ -150,7 +150,15 @@
     comment.enable = true;
     sleuth.enable = true;
 
-    rustaceanvim.enable = true;
+    rustaceanvim = {
+      enable = true;
+      settings = {
+        server = {
+          cmd = [ "${pkgs-unstable.rust-analyzer}/bin/rust-analyzer" ];
+        };
+      };
+    };
+
 
     mkdnflow = {
       enable = true;