CI: add cmake / ninja-build / libvulkan-dev / glslang-tools to ffmpeg-debian deps

The ffmpeg-v4l2-request-debian job now needs to build daedalus-fourier
into a temp prefix before configuring FFmpeg (substitution patch
0003-h264-idct4-daedalus-fourier.patch links libdaedalus_core.a into
libavcodec.so).  Mirror the build-deps the daedalus-v4l2-debian job
already declared for the same reason.

No-op on Arch — makepkg --syncdeps auto-installs cmake/ninja/
vulkan-headers from the PKGBUILD makedepends.

.gitea/workflows/build.yml

@@ -930,12 +930,13 @@ jobs:
           # map 1:1 to the previous Arch list; libav*-dev intentionally
           # absent (we are FFmpeg itself, providing those libs).
           retry apt-get install -y --no-install-recommends \
-              build-essential git pkg-config nasm yasm \
+              build-essential cmake ninja-build git pkg-config nasm yasm \
               linux-libc-dev libgl1-mesa-dev libasound2-dev libbz2-dev \
               libfontconfig-dev libfribidi-dev libgmp-dev libgnutls28-dev \
               libmp3lame-dev libass-dev libdav1d-dev libdrm-dev \
               libfreetype-dev libpulse-dev libva-dev libvorbis-dev libvpx-dev \
               libwebp-dev libx264-dev libx265-dev libxml2-dev libopus-dev \
+              libvulkan-dev glslang-tools \
               v4l-utils liblzma-dev zlib1g-dev \
               curl ca-certificates openssh-client rsync dpkg-dev