Remove tool.uv.sources table if it is empty (astral-sh#8365)

## Summary

Resolves astral-sh#8362

Author: j178

crates/uv-workspace/src/pyproject_mut.rs

@@ -539,6 +539,20 @@ impl PyProjectTomlMut {
         {
             if let Some(key) = find_source(name, sources) {
                 sources.remove(&key);
+
+                // Remove the `tool.uv.sources` table if it is empty.
+                if sources.is_empty() {
+                    self.doc
+                        .entry("tool")
+                        .or_insert(implicit())
+                        .as_table_mut()
+                        .ok_or(Error::MalformedSources)?
+                        .entry("uv")
+                        .or_insert(implicit())
+                        .as_table_mut()
+                        .ok_or(Error::MalformedSources)?
+                        .remove("sources");
+                }
             }
         }
 

crates/uv/tests/it/edit.rs

@@ -1688,8 +1688,6 @@ fn add_remove_workspace() -> Result<()> {
         [build-system]
         requires = ["setuptools>=42"]
         build-backend = "setuptools.build_meta"
-
-        [tool.uv.sources]
         "###
         );
     });
@@ -2881,8 +2879,6 @@ fn remove_non_normalized_source() -> Result<()> {
         [build-system]
         requires = ["setuptools>=42"]
         build-backend = "setuptools.build_meta"
-
-        [tool.uv.sources]
         "###
         );
     });
@@ -4614,8 +4610,6 @@ fn remove_repeated() -> Result<()> {
 
         [tool.uv]
         dev-dependencies = ["anyio"]
-
-        [tool.uv.sources]
         "###
         );
     });
@@ -4648,8 +4642,6 @@ fn remove_repeated() -> Result<()> {
 
         [tool.uv]
         dev-dependencies = ["anyio"]
-
-        [tool.uv.sources]
         "###
         );
     });
@@ -4685,8 +4677,6 @@ fn remove_repeated() -> Result<()> {
 
         [tool.uv]
         dev-dependencies = []
-
-        [tool.uv.sources]
         "###
         );
     });