Fix typo duplicate period in a docstring in the zipfile module. (GH-12326)

Lib/zipfile.py

@@ -879,7 +879,7 @@ class ZipExtFile(io.BufferedIOBase):
 
     def read(self, n=-1):
         """Read and return up to n bytes.
-        If the argument is omitted, None, or negative, data is read and returned until EOF is reached..
+        If the argument is omitted, None, or negative, data is read and returned until EOF is reached.
         """
         if n is None or n < 0:
             buf = self._readbuffer[self._offset:]