Use UTF8 by default in the environemt build

Tools like meson will fail if not
6 jobs for jjardon/utf8 in 203 minutes and 47 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Build
canceled #53646622
aarch64
build_aarch64

00:00:00

passed #53646620
x86_64
build_i586

03:23:47

passed #53646618
x86_64
build_x86_64

03:00:02

 
  Flatpak
skipped #53646624
aarch64
app_aarch64
skipped #53646623
x86_64
app_x86_64
 
  Vm
skipped #53646625
x86_64
minimal_vm_image_x86_64