Update to python3 basis

Author: Joe Atzberger

Dockerfile

@@ -1,9 +1,8 @@
 FROM hashicorp/terraform:0.12.29
-# FROM hashicorp/terraform:light # when we can support v.12+
 LABEL maintainer="Corelight AWS Team <aws@corelight.com>"
 LABEL description="Serverless with Terraform for CI/CD"
 
-RUN apk add --update git bash openssh make nodejs nodejs-npm
+RUN apk add --no-cache --update git bash openssh make nodejs nodejs-npm
 RUN npm install -g serverless \
     serverless-domain-manager \
     serverless-plugin-git-variables \
@@ -12,9 +11,9 @@ RUN npm install -g serverless \
 # Note: ignore "serverless update check failed" warning during "npm install"
 
 # Heavyweight considering we only use awscli for configuration, presently.
-RUN apk add --update python py-pip             && \
-    pip install --upgrade awscli python-gitlab && \
-    apk --purge del py-pip                     && \
-    rm /var/cache/apk/*
+RUN apk add --no-cache --update python3 py-pip groff && \
+    pip install --upgrade awscli python-gitlab
+
+RUN ln -s /usr/bin/python3 /usr/bin/python
 
 ENTRYPOINT ["/bin/bash", "-l", "-c"]