vagrant: add debian 11 "bullseye" box, fixes #5792

also making sure that the en_US.UTF-8 locale is present.

Vagrantfile

@@ -18,6 +18,8 @@ def packages_debianoid(user)
     apt install -y libssl-dev libacl1-dev liblz4-dev libzstd-dev pkg-config
     apt install -y libfuse-dev fuse || true
     apt install -y libfuse3-dev fuse3 || true
+    apt install -y locales || true
+    sed -i '/en_US.UTF-8/s/^# //g' /etc/locale.gen && locale-gen
     usermod -a -G fuse #{user}
     chgrp fuse /dev/fuse
     chmod 666 /dev/fuse
@@ -277,6 +279,22 @@ Vagrant.configure(2) do |config|
     b.vm.provision "run tests", :type => :shell, :privileged => false, :inline => run_tests("bionic64", ".*(fuse3|none).*")
   end
 
+  config.vm.define "bullseye64" do |b|
+    b.vm.box = "debian/bullseye64"
+    b.vm.provider :virtualbox do |v|
+      v.memory = 1024 + $wmem
+    end
+    b.vm.provision "fs init", :type => :shell, :inline => fs_init("vagrant")
+    b.vm.provision "packages debianoid", :type => :shell, :inline => packages_debianoid("vagrant")
+    b.vm.provision "install pyenv", :type => :shell, :privileged => false, :inline => install_pyenv("bullseye64")
+    b.vm.provision "install pythons", :type => :shell, :privileged => false, :inline => install_pythons("bullseye64")
+    b.vm.provision "build env", :type => :shell, :privileged => false, :inline => build_pyenv_venv("bullseye64")
+    b.vm.provision "install borg", :type => :shell, :privileged => false, :inline => install_borg("llfuse")
+    b.vm.provision "install pyinstaller", :type => :shell, :privileged => false, :inline => install_pyinstaller()
+    b.vm.provision "build binary with pyinstaller", :type => :shell, :privileged => false, :inline => build_binary_with_pyinstaller("bullseye64")
+    b.vm.provision "run tests", :type => :shell, :privileged => false, :inline => run_tests("bullseye64", ".*none.*")
+  end
+
   config.vm.define "buster64" do |b|
     b.vm.box = "debian/buster64"
     b.vm.provider :virtualbox do |v|