Add stub for pyicu

stubs/icu.pyi

@@ -0,0 +1,25 @@
+# Copyright 2022 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Stub for PyICU.
+
+class Locale:
+    @staticmethod
+    def getDefault() -> Locale: ...
+
+class BreakIterator:
+    @staticmethod
+    def createWordInstance(locale: Locale) -> BreakIterator: ...
+    def setText(self, text: str) -> None: ...
+    def nextBoundary(self) -> int: ...

synapse/storage/databases/main/user_directory.py

@@ -28,7 +28,7 @@
 
 try:
     # Figure out if ICU support is available for searching users.
-    import icu  # type: ignore[import]
+    import icu
 
     USE_ICU = True
 except ModuleNotFoundError: