2.66.1 (stable):

Glib:
* Variant: Fix template constructors so they work with C++20
  (Magne Oestlyngen) Merge request !50

Build:
* Meson build: Use relative paths to untracked/
  (Kjell Ahlstedt) Merge request gtkmm!61 (Mingli Yu)
* MSVC build: Export Glib::manage()
  (Chun-wei Fan) Merge request !48
* [gio|glib]mmconfig.h.*: Don't dllimport on MinGW
  (Chun-wei Fan) Issue gtkmm#90 (Lukas K.)
  (Chun-wei Fan) Merge reqest !49
* Meson build: examples and tests: Add dependency('threads')
  (Kjell Ahlstedt)
* Meson build: Make it possible to use glibmm as a subproject
  (Kjell Ahlstedt)
* Meson build: No implicit_include_directories
  (Kjell Ahlstedt)
* Meson build: Make quiet installations possible
  (Kjell Ahlstedt)
* MSVC build: Avoid exporting classes with std::string members
  (Chun-wei Fan) Merge reqest !52