Sort distributions when computing hash (#9185)

## Summary

The distributions used to be stored in a `BTreeMap`, keyed by name.
They're now stored in a graph... so iteration isn't guaranteed to
produce a deterministic hash!

This fixes a "flaky" test, though it's actually a real bug. The test was
right!

Closes #9137.

crates/uv/src/commands/project/environment.rs

@@ -11,7 +11,7 @@ use uv_cache::{Cache, CacheBucket};
 use uv_cache_key::{cache_digest, hash_digest};
 use uv_client::Connectivity;
 use uv_configuration::{Concurrency, TrustedHost};
-use uv_distribution_types::Resolution;
+use uv_distribution_types::{Name, Resolution};
 use uv_python::{Interpreter, PythonEnvironment};
 
 /// A [`PythonEnvironment`] stored in the cache.
@@ -79,7 +79,8 @@ impl CachedEnvironment {
         // TODO(charlie): If the resolution contains any mutable metadata (like a path or URL
         // dependency), skip this step.
         let resolution_hash = {
-            let distributions = resolution.distributions().collect::<Vec<_>>();
+            let mut distributions = resolution.distributions().collect::<Vec<_>>();
+            distributions.sort_unstable_by_key(|dist| dist.name());
             hash_digest(&distributions)
         };