fix: copy attributes passed from the user to avoid mutation

changes/4059.bugfix.md

@@ -0,0 +1 @@
+Prevents mutation of the attributes dict provided by the user by copying them instead of keeping the reference

src/zarr/core/group.py

@@ -105,7 +105,7 @@ def parse_attributes(data: Any) -> dict[str, Any]:
     if data is None:
         return {}
     elif isinstance(data, dict) and all(isinstance(k, str) for k in data):
-        return data
+        return dict(data)
     msg = f"Expected dict with string keys. Got {type(data)} instead."
     raise TypeError(msg)
 

src/zarr/core/metadata/common.py

@@ -10,4 +10,4 @@ def parse_attributes(data: dict[str, JSON] | None) -> dict[str, JSON]:
     if data is None:
         return {}
 
-    return data
+    return dict(data)