Install vsutil with pip

This also changes how getnative is installed, because I can’t do a
sed on every setup.py.

Dockerfile

@@ -123,21 +123,17 @@ RUN mkdir /usr/local/lib/vapoursynth-scripts/ \
         https://github.com/IFeelBloated/vapoursynth-mvtools-sf/raw/5dfa8756092daa7dcc635eef799c6964bd40c259/src/mvmulti.py \
         https://github.com/Irrational-Encoding-Wizardry/fvsfunc/raw/master/fvsfunc.py \
         https://github.com/Irrational-Encoding-Wizardry/kagefunc/raw/master/kagefunc.py \
-        https://github.com/Irrational-Encoding-Wizardry/vsutil/raw/master/vsutil.py \
         https://github.com/WolframRhodium/muvsfunc/raw/master/Collections/muvsfunc_numpy.py \
         https://github.com/WolframRhodium/muvsfunc/raw/master/muvsfunc.py \
         https://github.com/dubhater/vapoursynth-adjust/raw/master/adjust.py \
         https://github.com/theChaosCoder/lostfunc/raw/master/lostfunc.py \
     && chmod 755 /usr/local/lib/vapoursynth-scripts/*
 
-# Installing that way because I use the system (dmo) VapourSynth and want to
-# avoid conflicts
-RUN git clone --depth=1 https://github.com/Infiziert90/getnative \
-    && cd getnative \
-    && sed -i -e 's/VapourSynth.*//' requirements.txt \
-    && pip3 install . \
-    && cd .. \
-    && rm -rf getnative
+# kinda dumb (vapoursynth gets built), but I do not know how to do this better
+RUN pip3 install -t /usr/local/lib/vapoursynth-scripts/ --no-cache-dir \
+        getnative \
+        vsutil \
+    && pip3 uninstall -y vapoursynth
 
 RUN adduser --disabled-password --gecos '' vapoursynth
 USER vapoursynth