feat: tests on Python 3.14

[BoboTiG]

• Python 3.7 is EOL since 2023-06-27, and it's no more "easy" to use in the CI. Lets move on.
• Python 3.14-dev is not yet working on Windows:

  Microsoft (R) Library Manager Version 14.42.34436.0
  Copyright (C) Microsoft Corporation.  All rights reserved.
  
  running build_ext
  building 'marisa_trie' extension
  creating build\temp.win-amd64-cpython-314\Release\src
  "C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.42.34433\bin\HostX86\x64\cl.exe" /c /nologo /O2 /W3 /GL /DNDEBUG /MD -Imarisa-trie\include -IC:\hostedtoolcache\windows\Python\3.14.0-alpha.5\x64\include -IC:\hostedtoolcache\windows\Python\3.14.0-alpha.5\x64\Include "-IC:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.42.34433\include" "-IC:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Tools\MSVC\14.42.34433\ATLMFC\include" "-IC:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC\Auxiliary\VS\include" "-IC:\Program Files (x86)\Windows Kits\10\include\10.0.26100.0\ucrt" "-IC:\Program Files (x86)\Windows Kits\10\\include\10.0.26100.0\\um" "-IC:\Program Files (x86)\Windows Kits\10\\include\10.0.26100.0\\shared" "-IC:\Program Files (x86)\Windows Kits\10\\include\10.0.26100.0\\winrt" "-IC:\Program Files (x86)\Windows Kits\10\\include\10.0.26100.0\\cppwinrt" "-IC:\Program Files (x86)\Windows Kits\NETFXSDK\4.8\include\um" /EHsc /Tpsrc/agent.cpp /Fobuild\temp.win-amd64-cpython-314\Release\src\agent.obj
  agent.cpp
  C:\hostedtoolcache\windows\Python\3.14.0-alpha.5\x64\include\internal\pycore_stackref.h(278): error C7555: use of designated initializers requires at least '/std:c++20'
  C:\hostedtoolcache\windows\Python\3.14.0-alpha.5\x64\include\internal\pycore_stackref.h(278): error C2737: 'PyStackRef_NULL': const object must be initialized
  C:\hostedtoolcache\windows\Python\3.14.0-alpha.5\x64\include\internal/pycore_frame.h(195): error C7555: use of designated initializers requires at least '/std:c++20'
  C:\hostedtoolcache\windows\Python\3.14.0-alpha.5\x64\include\internal/pycore_frame.h(195): error C4576: a parenthesized type followed by an initializer list is a non-standard explicit type conversion syntax
  C:\hostedtoolcache\windows\Python\3.14.0-alpha.5\x64\include\internal/pycore_frame.h(370): error C7555: use of designated initializers requires at least '/std:c++20'
  C:\hostedtoolcache\windows\Python\3.14.0-alpha.5\x64\include\internal/pycore_frame.h(370): error C4576: a parenthesized type followed by an initializer list is a non-standard explicit type conversion syntax
  C:\hostedtoolcache\windows\Python\3.14.0-alpha.5\x64\include\internal/pycore_frame.h(371): error C7555: use of designated initializers requires at least '/std:c++20'
  C:\hostedtoolcache\windows\Python\3.14.0-alpha.5\x64\include\internal/pycore_frame.h(371): error C4576: a parenthesized type followed by an initializer list is a non-standard explicit type conversion syntax
  error: command 'C:\\Program Files\\Microsoft Visual Studio\\2022\\Enterprise\\VC\\Tools\\MSVC\\14.42.34433\\bin\\HostX86\\x64\\cl.exe' failed with exit code 2