bug: fcs_file.channels is List[str], not str

Author: zbjornson

cellengine/resources/fcs_file.py

@@ -76,7 +76,7 @@ def annotations(self, val):
             self._annotations = val
 
     @property
-    def channels(self) -> List:
+    def channels(self) -> List[str]:
         """Return all channels in the file"""
         return [f["channel"] for f in self.panel]  # type: ignore