fix typo

Author: zm711

src/spikeinterface/core/analyzer_extension_core.py

@@ -23,7 +23,7 @@
 class ComputeRandomSpikes(AnalyzerExtension):
     """
     AnalyzerExtension that select somes random spikes.
-    This is allows for a subsampling of spikes for further calculations and is important
+    This allows for a subsampling of spikes for further calculations and is important
     for managing that amount of memory and speed of computation in the analyzer.
 
     This will be used by the `waveforms`/`templates` extensions.