Fix Dockerfile lint errors

Author: smerrell

Dockerfile

@@ -1,8 +1,10 @@
 ARG TF_AZ_CLI_VERSION=release-5.1_terraform-0.12.29_azcli-2.15.1
 FROM zenika/terraform-azure-cli:${TF_AZ_CLI_VERSION} AS build
 
-RUN apt-get update && apt-get install git python3-pip -y
-RUN pip3 install gitpython python-terraform pyhcl
+RUN apt-get update && \
+    apt-get install --no-install-recommends git=1:2.20.1-2+deb10u3 python3-pip=18.1-5 -y && \
+    apt-get clean && rm -rf /var/lib/apt/lists/*
+RUN pip3 install gitpython==3.1.12 python-terraform==0.10.1 pyhcl==0.4.4
 
 FROM build as final
 WORKDIR /workspace