dockerfile-guix: set locale to fix some installation, such as pelican package

dockerfile-guix

@@ -50,5 +50,8 @@ RUN /usr/local/bin/guix-daemon-wrapper.sh guix install hello
 # Add the updated guix in the PATH and path to executables installed with guix install
 ENV PATH="/root/.guix-profile/bin":"/root/.config/guix/current/bin":$PATH
 
+# set locale (should be fixed in future guix)
+ENV LC_ALL="C.UTF-8"
+
 ## Execute this first before executing guix commands in a container:
 #/var/guix/profiles/per-user/root/current-guix/bin/guix-daemon --build-users-group=guixbuild --disable-chroot --substitute-urls='https://bordeaux.guix.gnu.org https://ci.guix.gnu.org https://guix.bordeaux.inria.fr' &