refactor(nix-compat/nixhash): use SRI hashes for Display

This is probably a nicer default, and also aligns more with Serialize.

Change-Id: I3a8f18607c305dbf9fb93a2e2dd02ad07cd99f24
Reviewed-on: https://cl.tvl.fyi/c/depot/+/13161
Reviewed-by: Ilan Joselevich <personal@ilanjoselevich.com>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

tvix/nix-compat/src/nixhash/mod.rs

@@ -46,7 +46,7 @@ impl Display for NixHash {
             f,
             "{}-{}",
             self.algo(),
-            nixbase32::encode(self.digest_as_bytes())
+            BASE64.encode(self.digest_as_bytes())
         )
     }
 }