chore: bump Rust toolchain to 1.81.0 (#2227)

The Rust 1.81 toolchain fixed the hashing of Path objects. Previously,
paths were hashed equally wether they contained a slash or not. This is
not the case anymore which is definitely fixing a bug.

However, it does break existing hashes in the task cache or in lockfiles
for editable installs, which is unfortunate for us.

---------

Co-authored-by: Tim de Jager <tim@prefix.dev>

pixi.toml

@@ -72,7 +72,7 @@ toml-lint = "taplo lint --verbose **/pixi.toml"
 git = ">=2.46.0,<3"
 openssl = "3.*"
 pkg-config = "0.29.*"
-rust = "~=1.80.0"
+rust = "~=1.81.0"
 [feature.build.target.linux-64.dependencies]
 clang = ">=18.1.8,<19.0"
 compilers = ">=1.6.0"

rust-toolchain

@@ -1 +1 @@
-1.80.0
+1.81.0

src/task/file_hashes.rs

@@ -226,7 +226,7 @@ mod test {
             let mut hasher = Xxh3::new();
             hashes.hash(&mut hasher);
             let s = format!("{:x}", hasher.finish());
-            assert_eq!(s, "be05bb5d7c6e8e6");
+            assert_eq!(s, "722d374e94c4dcfc");
         }
 
         let hashes = FileHashes::from_files(target_dir.path(), vec!["src/"])