Log Message:
glibmm: updated to 2.66.7

2.66.7 (stable):

Gio:
* content_type_guess(): Remove most of an unnecessary overload

Documentation:
* Gio::File: Fix various spelling errors
* Remove AUTHORS and README.SUN; add info to README.md

gmmproc:
* enum.pl, enumextract.py: Accept XXX = YYY + 1
* h2def.py: Make return types that are unsigned work.
  Required by gtkmm4, GdkDmabufTextureBuilder

Tests:
* Giomm tests: Test for /etc/passwd instead of /etc/fstab

Build:
* Meson build: Don't fail if warning_level=everything
* MSVC, NMake: Make dep paths configurable