CMake: Bump min required CMake version for static Qt builds to 3.21

Building a static library Qt configuration will now require a
minimum CMake version of 3.21.

Using such a static library Qt configuration in user projects will now
require the same minimum CMake version of 3.21.

Qt builders and packagers can still opt out of the mentioned minimum
required version by configuring Qt with
QT_FORCE_MIN_CMAKE_VERSION_FOR_BUILDING_QT
and
QT_FORCE_MIN_CMAKE_VERSION_FOR_USING_QT.

Such a Qt configuration is /NOT SUPPORTED/.

Increase the upper range of CMake policies set to NEW to 3.21.

Amends 9aa0d99
Amends 6518bcc

[ChangeLog][CMake] Building Qt as static libraries now requires
CMake version 3.21 or later. Building user projects with CMake using
that Qt installation also requires a CMake version of 3.21 or later.

Pick-to: 6.2
Fixes: QTBUG-95018
Change-Id: I717b6e1207df46627443b3e5ed430f3c964e2b48
Reviewed-by: Joerg Bornemann <[email protected]>

.cmake.conf

@@ -3,13 +3,13 @@ set(QT_REPO_MODULE_PRERELEASE_VERSION_SEGMENT "alpha1")
 
 # Minimum requirement for building Qt
 set(QT_SUPPORTED_MIN_CMAKE_VERSION_FOR_BUILDING_QT_SHARED "3.16")
-set(QT_SUPPORTED_MIN_CMAKE_VERSION_FOR_BUILDING_QT_STATIC "3.20")
+set(QT_SUPPORTED_MIN_CMAKE_VERSION_FOR_BUILDING_QT_STATIC "3.21")
 
 # Minimum requirement for consuming Qt in a user project.
 # This might be different in the future, e.g. be lower than the requirement for
 # building Qt.
 set(QT_SUPPORTED_MIN_CMAKE_VERSION_FOR_USING_QT_SHARED "3.16")
-set(QT_SUPPORTED_MIN_CMAKE_VERSION_FOR_USING_QT_STATIC "3.20")
+set(QT_SUPPORTED_MIN_CMAKE_VERSION_FOR_USING_QT_STATIC "3.21")
 
 # Policy settings for commands defined by qtbase. These will also be injected
 # into the top level policy scope of each Qt module when building Qt so that
@@ -21,4 +21,4 @@ set(QT_SUPPORTED_MIN_CMAKE_VERSION_FOR_USING_QT_STATIC "3.20")
 #       opportunity for substituting the values from here. Keep both locations
 #       in sync.
 set(QT_MIN_NEW_POLICY_CMAKE_VERSION "3.16")
-set(QT_MAX_NEW_POLICY_CMAKE_VERSION "3.20")
+set(QT_MAX_NEW_POLICY_CMAKE_VERSION "3.21")