Use the build cache more efficiently

Dockerfile

@@ -3,28 +3,12 @@ FROM debian:testing
 RUN echo 'deb http://ftp-stud.hs-esslingen.de/pub/Mirrors/debian-multimedia/ testing main' > /etc/apt/sources.list.d/deb-multimedia.list \
     && apt-get update -oAcquire::AllowInsecureRepositories=true \
     && apt-get -y --allow-unauthenticated install deb-multimedia-keyring \
-    && rm -rf /var/lib/apt/lists
+    && apt-get update
 
-RUN apt-get update \
-    && apt-get -y install \
-        autoconf \
-        beignet-opencl-icd \
-        clinfo \
-        ffmpeg \
-        git \
-        libplacebo-dev \
-        libtool \
-        meson \
-        mkvtoolnix \
-        pocl-opencl-icd \
-        python3-opencv \
-        python3-pip \
-        vapoursynth \
-        vapoursynth-* \
-        wget \
-        x264 \
-        x265 \
-    && rm -rf /var/lib/apt/lists
+# Base build dependencies
+RUN apt-get -y install \
+        build-essential \
+        wget
 
 # required for DCTFilter
 RUN cd /tmp \
@@ -42,6 +26,16 @@ RUN cd /tmp \
     && cd .. \
     && rm -rf fftw-3.3.8
 
+# Vapoursynth plugin build dependencies
+RUN apt-get -y install \
+        autoconf \
+        cargo \
+        git \
+        libplacebo-dev \
+        libtool \
+        meson \
+        vapoursynth-dev
+
 # required by hvf.Deblock_QED (required by fvf.AutoDeblock)
 RUN cd /tmp \
     && git clone --depth=1 https://github.com/HomeOfVapourSynthEvolution/VapourSynth-DCTFilter \
@@ -65,7 +59,7 @@ RUN cd /tmp \
     && rm -rf VS-ContinuityFixer
 
 # double speed for getnative
-RUN cd /tmp/ \
+RUN cd /tmp \
     && git clone --depth=1 https://github.com/OrangeChannel/vapoursynth-descale \
     && cd vapoursynth-descale \
     && g++ -std=c++17 -shared -fPIC -O2 descale.cpp -o libdescale_getnative.so \
@@ -84,6 +78,19 @@ RUN cd /tmp \
     && cd /tmp/ \
     && rm -rf vs-placebo
 
+# Runtime dependencies
+RUN apt-get -y install \
+        beignet-opencl-icd \
+        clinfo \
+        ffmpeg \
+        mkvtoolnix \
+        pocl-opencl-icd \
+        python3-opencv \
+        python3-pip \
+        vapoursynth-* \
+        x264 \
+        x265
+
 RUN pip3 --no-cache-dir install \
         matplotlib \
         tqdm \