Fix CMake warnings about deprecated target SQLite::SQLite3

[MeanSquaredError]

Trying to build sqlpp23 with CMake 4.3.0 and the following command line

cmake -B build -G Ninja -DBUILD_POSTGRESQL_CONNECTOR=ON -DBUILD_SQLITE3_CONNECTOR=ON -DBUILD_MYSQL_CONNECTOR=ON -DBUILD_TESTING=ON -DDEPENDENCY_CHECK=ON -DBUILD_WITH_MODULES=ON

will show a whole bunch of repeating warnings saying the following

CMake Warning (dev) at cmake/Sqlpp23TargetHelper.cmake:161 (target_link_libraries):
  The library that is being linked to, SQLite::SQLite3, is marked as being
  deprecated by the owner.  The message provided by the developer is:

  The target name SQLite::SQLite3 is deprecated.  Please use SQLite3::SQLite3
  instead.

Call Stack (most recent call first):
  cmake/Sqlpp23TargetHelper.cmake:111 (add_common)
  cmake/Sqlpp23TargetHelper.cmake:62 (add_regular_and_module)
  CMakeLists.txt:63 (add_component)
This warning is for project developers.  Use -Wno-dev to suppress it.

The CMake script that searches for SQLite3 and creates the targets is not provided by SQLite3 but comes with CMake itself, so I checked the source code at https://github.com/Kitware/CMake/blob/master/Modules/FindSQLite3.cmake
and the comments in the script pretty much confirmed what the comments say: with CMake 4.3.0 or newer the target should be SQLite3::SQLite3 instead of the old SQLite::SQLite3

So this fix checks the CMake version and uses the appropriate target.

[rbock]

Thanks for the fix.

FYI, I am still on CMake 3.31

[MeanSquaredError]

Well, in my case I am using Fedora 44, which defaults to CMake 4.3.0, and it actually updated to that version even without asking me whether I want that update. Well, it probably did ask at some point, but I just confirmed the update without checking what is actually being installed :-)

BTW I strongly suspect that the other build error, which I get when it tries to build the sqlpp core tests is caused at least partially by the new CMake version too. I am still investigating it and hopefully will find a fix (or at least a workaround) today.