Use CMake version range to support CMake 3.30 and newer (#51)

PTLConfig's use of a single version in cmake_minimum_required results
in a warning:

```
CMake Deprecation Warning at build/source/externals/ptl/PTLConfig.cmake:30 (cmake_minimum_required):
  Compatibility with CMake < 3.10 will be removed from a future version of
  CMake.

  Update the VERSION argument <min> value or use a ...<max> suffix to tell
  CMake that the project does not need compatibility with older versions.
```

Use ...<max> suffix to state compatibility with newer versions and
resolve warning.

cmake/Templates/PTLConfig.cmake.in

@@ -3,7 +3,7 @@
 #
 @PACKAGE_INIT@
 
-cmake_minimum_required(VERSION 3.8)
+cmake_minimum_required(VERSION 3.8...3.27)
 
 # -------------------------------------------------------------------------------------- #
 # basic paths