Minor nits to whats new tail call wording (#130912)

Author: Fidget-Spinner

Doc/whatsnew/3.14.rst

@@ -297,7 +297,7 @@ For further information on how to build Python, see
 
 .. attention::
 
-    This section previously reported a 9-15% geomean speedup. This number has since been
+    This section previously reported a 9-15% geometric mean speedup. This number has since been
     cautiously revised down to 3-5%. While we expect performance results to be better
     than what we report, our estimates are more conservative due to a
     `compiler bug <https://github.com/llvm/llvm-project/issues/106846>`_ found in