Fix references to CMake in case of C17 and C23

With the C17 and C23 templates one must have at least CMake 3.21,
because support for those standards was added in that version.

README.md

@@ -93,7 +93,7 @@ libraries! (Part 2)](https://www.youtube.com/watch?v=_5weX5mx8hc)
 Make sure you have these programs installed:
 
 * Python 3.8 or newer
-* CMake 3.20 or newer
+* CMake 3.20 or newer (3.21 or newer for C17 or newer projects)
 * git
 * [clang-tidy 14](#clang-tidy) (optional)
 * [cppcheck](#cppcheck) (optional)

cmake-init/cmake_init.py

@@ -366,13 +366,14 @@ def create(args, zip):
     for zip_path in (f"templates/{p}" for p in zip_paths):
         write_dir(path, d, args.overwrite, zipfile.Path(zip, zip_path))
     git_init(path)
-    print("""\
+    cmake_version = "3.21" if d["cmake_321"] else "3.20"
+    print(f"""\
 To get started with developing the project, make sure you read the generated
 HACKING.md and BUILDING.md files for how to build the project as a developer or
 as a user respectively. There are also some details you may want to fill in in
 the README.md, CONTRIBUTING.md and .github/workflows/ci.yml files.
 
-Now make sure you have at least CMake 3.20 installed for local development, to
+Now make sure you have at least CMake {cmake_version} installed for local development, to
 make use of all the nice Quality-of-Life improvements in newer releases:
 https://cmake.org/download/