Config a multi stage optimisation, and remove unused ENV variable

Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:21.10
+FROM ubuntu:21.10 AS blender
 
 # Setup all software version request
 ARG b3d_vs_major=2.90
@@ -7,8 +7,6 @@ ARG b3d_vs_minor=0
 LABEL Author="stilobique"
 LABEL Title="Blender Docker for Unit Test"
 
-ENV B3D_ADDON_PATH "/bin/blender/${b3d_vs_major}/scripts/addons"
-
 # Install dependencies
 RUN apt-get update && apt-get install -y \
     zip \
@@ -27,5 +25,9 @@ RUN wget https://download.blender.org/release/Blender${b3d_vs_major}/blender-${b
     && rm -rf /opt/blender-${b3d_vs_major}.${b3d_vs_minor}-linux-x64.tar.xz \
     && mv /opt/blender-${b3d_vs_major}.${b3d_vs_minor}-linux-x64 /opt/blender
 
+# Setup a Multistage optimisation
+FROM ubuntu:21.10
+COPY --from=blender /opt/blender/ /
+
 # Working Directory setup
 WORKDIR /