Fix some typos.

Found with https://github.com/intgr/topy/
diff --git a/tests/test_utils.py b/tests/test_utils.py
index b50c21f..7a0b9e7 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -2638,7 +2638,7 @@
 
 
 def test_raises_unsupported_algorithm():
-    # Check that it doesnt assert if the right things are raised.
+    # Check that it doesn't assert if the right things are raised.
     with raises_unsupported_algorithm(
         _Reasons.BACKEND_MISSING_INTERFACE
     ) as exc_info: