chore(tvix): fix trivial clippy lints

Relates to b/321.

Change-Id: I37284f89b186e469eb432e2bbedb37aa125a6ad4
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9961
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>
Autosubmit: tazjin <tazjin@tvl.su>

tvix/eval/src/vm/mod.rs

@@ -406,7 +406,7 @@ impl<'o> VM<'o> {
             .pop()
             .expect("tvix bug: runtime stack empty after execution");
         Ok(RuntimeResult {
-            value: value,
+            value,
             warnings: self.warnings,
         })
     }