cmake: Update to 3.20.4

cmake: Update to 3.20.4

- Update from 3.20.3 to 3.20.4
- Update of rootfile not required.
- Changelog
   Changes in 3.20.4 since 3.20.3:
    Ben Boeckel (1):
      ci: use consistent sccache builds
    Brad King (8):
      VS: Add special case for '-T version=14.29.16.10' under VS 16.10
      VS: Add flag table entries for '/external:W*' flags in VS 16.10
      gitlab-ci: Update Windows builds to MSVC 19.29-16.10 toolset
      Makefiles: Fix CMAKE_EXPORT_COMPILE_COMMANDS crash with custom compile rule
      presets: Fix buildPreset "jobs" field test case
      IRSL: Add Intel oneAPI redist location on Windows
      fileapi: Fix codemodel-v2 link command fragment relative paths
    John Drouhard (1):
      FindBoost: Add check for json component header in Boost 1.75+
    Marc Chevrier (1):
      Help: cmake_path: fix erroneous example for IS_PREFIX
    Raul Tambre (2):
      MSVC: C++20 final flag, C++23 support
      Clang/MSVC: C++20 final flag, C++23 support
    Sam Freed (2):
      presets: Fix buildPreset "jobs"
      presets: Fix buildPreset "targets" not allowing a single string

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>