Add release notes and bump version for 0.8.0 (#14690)

[Rendered](https://github.com/astral-sh/uv/blob/zb/release-notes/CHANGELOG.md)

crates/uv-build-backend/src/lib.rs

@@ -557,7 +557,7 @@ mod tests {
         // Check that the source dist is reproducible across platforms.
         assert_snapshot!(
             format!("{:x}", sha2::Sha256::digest(fs_err::read(&source_dist_path).unwrap())),
-            @"dab46bcc4d66960a11cfdc19604512a8e1a3241a67536f7e962166760e9c575c"
+            @"9a7f7181c5e69ac14e411a2500fed153a1e6ea41cd5da6f24f226c4cddacf6b7"
         );
         // Check both the files we report and the actual files
         assert_snapshot!(format_file_list(build.source_dist_list_files, src.path()), @r"