Fix a small typo in a comment (#2863)

diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 3953fec..eaa7b7f 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -535,7 +535,7 @@
  * safe to call without calling Py_Initialize first)
  */
 
-/* TODO: Progresively move functionality from Py_BeginInitialization to
+/* TODO: Progressively move functionality from Py_BeginInitialization to
  * Py_ReadConfig and Py_EndInitialization
  */