Show something useful from EvtSubscribe_push demo (#2281)

CHANGES.txt

@@ -14,6 +14,7 @@ https://mhammond.github.io/pywin32_installers.html.
 Coming in build 309, as yet unreleased
 --------------------------------------
 
+* The `EvtSubscribe_push` demo now actually demonstrates the callback action and the event context being filled. (#2281, @Avasam)
 * Fixed Pythonwin's editor failing due to invalid regex import (#2419, @Avasam)
 * Last error wrongly set by some modules (#2302, @CristiFati)
 * Dropped support for Python 3.7 (#2207, @Avasam)

win32/Demos/EvtSubscribe_push.py

@@ -1,4 +1,8 @@
 ## Demonstrates a "push" subscription with a callback function
+from __future__ import annotations
+
+from time import sleep
+
 import win32evtlog
 
 query_text = '*[System[Provider[@Name="Microsoft-Windows-Winlogon"]]]'
@@ -15,11 +19,14 @@ def c(reason, context, evt):
     return 0
 
 
-evttext = []
+evttext: list[str] = []
 s = win32evtlog.EvtSubscribe(
     "System",
     win32evtlog.EvtSubscribeStartAtOldestRecord,
     Query="*",
     Callback=c,
     Context=evttext,
 )
+
+sleep(0.001)
+print("\n".join(evttext))