chore(tvix/castore): remove dependency on anyhow

We don't use this here, except in a test, where we don't really use
it either.

Change-Id: Ia6c45fccf663fe328942b1e1a2cd1c3a1b7f9ae5
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9376
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: Connor Brewster <cbrewster@hey.com>
Tested-by: BuildkiteCI

tvix/Cargo.nix

@@ -8136,10 +8136,6 @@ rec {
           then lib.cleanSourceWith { filter = sourceFilter; src = ./castore; }
           else ./castore;
         dependencies = [
-          {
-            name = "anyhow";
-            packageId = "anyhow";
-          }
           {
             name = "async-stream";
             packageId = "async-stream";