move cache to module level

pyiceberg/table/snapshots.py

@@ -229,6 +229,15 @@ def __eq__(self, other: Any) -> bool:
         )
 
 
+@lru_cache
+def _manifests(io: FileIO, manifest_list: Optional[str]) -> List[ManifestFile]:
+    """Return the manifests from the manifest list."""
+    if manifest_list not in (None, ""):
+        file = io.new_input(manifest_list)  # type: ignore
+        return list(read_manifest_list(file))
+    return []
+
+
 class Snapshot(IcebergBaseModel):
     snapshot_id: int = Field(alias="snapshot-id")
     parent_snapshot_id: Optional[int] = Field(alias="parent-snapshot-id", default=None)
@@ -248,18 +257,9 @@ def __str__(self) -> str:
         result_str = f"{operation}id={self.snapshot_id}{parent_id}{schema_id}"
         return result_str
 
-    @staticmethod
-    @lru_cache
-    def _manifests(io: FileIO, manifest_list: Optional[str]) -> List[ManifestFile]:
-        """Return the manifests for the given snapshot."""
-        if manifest_list not in (None, ""):
-            file = io.new_input(manifest_list)  # type: ignore
-            return list(read_manifest_list(file))
-        return []
-
     def manifests(self, io: FileIO) -> List[ManifestFile]:
         """Return the manifests for the given snapshot."""
-        return Snapshot._manifests(io, self.manifest_list)
+        return _manifests(io, self.manifest_list)
 
 
 class MetadataLogEntry(IcebergBaseModel):