Fix CMake CMP0135 configure warning

[aloisklink]

On CMake v3.24.0, edgesec currently prints the following warning multiple times:

CMake Warning (dev) at /snap/cmake/1147/share/cmake-3.24/Modules/ExternalProject.cmake:3071 (message):
  The DOWNLOAD_EXTRACT_TIMESTAMP option was not given and policy CMP0135 is
  not set.  The policy's OLD behavior will be used.  When using a URL
  download, the timestamps of extracted files should preferably be that of
  the time of extraction, otherwise code that depends on the extracted
  contents might not be rebuilt if the URL changes.  The OLD behavior
  preserves the timestamps from the archive instead, but this is usually not
  what you want.  Update your project to the NEW behavior or specify the
  DOWNLOAD_EXTRACT_TIMESTAMP option with a value of true to avoid this
  robustness issue.

By setting cmake_policy(VERSION 3.14.0...3.24.0), CMake will automatically enable all policies up to version v3.24.0, which hides these warnings.

We have to remove all the cmake_minimum_required... commands from the lib/ directory, since otherwise they overwrite the settings from the root CMakeLists.txt.

[codecov]

Codecov Report

Merging #231 (79c8000) into main (c904824) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #231   +/-   ##
=======================================
  Coverage   45.56%   45.56%           
=======================================
  Files         108      108           
  Lines       14949    14949           
=======================================
  Hits         6811     6811           
  Misses       8138     8138           

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