CI ARM: build Vulkan with armhf

This effectively reverts commit 02cd247 (later modified to disable
Vulkan only for 32b ARM).

Author: MartinPulec

.github/scripts/Linux/arm/bootstrap.sh

@@ -32,6 +32,7 @@ apt -y install \
   libdrm-dev\
   libsdl2-dev libsdl2-mixer-dev libsdl2-ttf-dev\
   libva-dev\
+  libvulkan-dev\
 
 /.github/scripts/install-common-deps.sh
 /.github/scripts/Linux/install_others.sh ndi pipewire ximea

.github/scripts/Linux/arm/build.sh

@@ -13,9 +13,6 @@ APPNAME=UltraGrid-latest-${ARCH}.AppImage
 # shellcheck disable=SC2086 # intentional
 set -- $FEATURES
 set -- "$@" --enable-drm_disp
-if [ "$ARCH" != arm64 ]; then
-        set -- "$@" --disable-vulkan
-fi
 
 ./autogen.sh "$@"
 make -j "$(nproc)"