Updated Qt to 5.15.17 on Windows.

Telegram/build/prepare/prepare.py

@@ -1557,7 +1557,6 @@ release:
 depends:patches/qtbase_""" + qt + """/*.patch
     cd qtbase
 win:
-    git revert --no-edit 6ad56dce34
     setlocal enabledelayedexpansion
     for /r %%i in (..\\..\\patches\\qtbase_%QT%\\*) do (
         git apply %%i -v

Telegram/build/qt_version.py

@@ -9,5 +9,5 @@ def resolve(arch):
             os.environ['QT'] = '6.9.1'
         else:
             print('Choosing Qt 5.')
-            os.environ['QT'] = '5.15.15'
+            os.environ['QT'] = '5.15.17'
     return True