Enable mypy for synapse.util.caches (#8547)

This seemed to entail dragging in a type stub for SortedList.

1 files changed, 1 insertions, 1 deletions

diff --git a/synapse/util/caches/ttlcache.py b/synapse/util/caches/ttlcache.py

index 3e180cafd3..6ce2a3d12b 100644
--- a/synapse/util/caches/ttlcache.py
+++ b/synapse/util/caches/ttlcache.py
@@ -34,7 +34,7 @@ class TTLCache:
         self._data = {}
 
         # the _CacheEntries, sorted by expiry time
-        self._expiry_list = SortedList()
+        self._expiry_list = SortedList()  # type: SortedList[_CacheEntry]
 
         self._timer = timer