Only do shallow clones

Dockerfile

@@ -9,14 +9,14 @@ RUN mkdir -p ~/.gradle \
 
 # Now grab some source code and run a minimal Gradle build to force fetching of wrappers and any immediate dependencies
 RUN cd ~/ws \
-    && git clone https://github.com/MovingBlocks/joml-ext.git \
+    && git clone --depth 1 https://github.com/MovingBlocks/joml-ext.git \
     && cd joml-ext \
     &&  ./gradlew compileTestJava \
     && rm -rf ~/ws/joml-ext
 
 # This step builds the Terasology engine. As a special step it prepares a "build harness" to build modules standalone
 RUN cd ~/ws \
-    && git clone https://github.com/MovingBlocks/Terasology.git \
+    && git clone --depth 1 https://github.com/MovingBlocks/Terasology.git \
     && cd Terasology \
     &&  ./gradlew extractNatives extractConfig compileTestJava \
     && mkdir -p ~/ws/harness &&  mkdir -p ~/ws/harness/build-logic/src \
@@ -32,7 +32,7 @@ RUN cd ~/ws \
     && rm -rf ~/ws/Terasology
 
 RUN cd ~/ws \
-    && git clone https://github.com/Terasology/Sample.git \
+    && git clone --depth 1 https://github.com/Terasology/Sample.git \
     && cd Sample \
     && cp -r ~/ws/harness/* . \
     && ./gradlew compileTestJava \