…ronment fails

[#89] cppcms_error fix typo + consistent  messages

Fixes scores of errors like:
	SyntaxWarning: invalid escape sequence '\*'

Using invalid escape sequences in string literals has been deprecated since Python 3.6.
Since then, attempting to use an invalid escape sequence has emitted a DeprecationWarning.
Python 3.12 upgraded the DeprecationWarning to a SyntaxWarning.

Python 3.12 compatibility: wrap regex in r''.

because std::system_category does not translate WSAGetLastError results

The build with CMake >= 4 currently fails with:

CMake Error at CMakeLists.txt:1 (cmake_minimum_required):
  Compatibility with CMake < 3.5 has been removed from CMake.

  Update the VERSION argument <min> value.  Or, use the <min>...<max> syntax
  to tell CMake that the project requires at least <min> but has been updated
  to work with policies introduced by <max> or earlier.

  Or, add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 to try configuring anyway.

we simply need to specify that the minimum version is 3.5 to fix the
build.

Signed-off-by: Thomas Petazzoni <[email protected]>

CMakeLists.txt: make it compatible with CMake 4