tooling(delete-rem-tags): pass git commit info

Passes git author information via environment variables into the docker
container, in order to ensure commits done by the script have correct
author information.

Makefile

@@ -44,7 +44,7 @@ DOCKER_TEX_VOLUME = -v "$(dir $(realpath $<)):/data" -w "/data"
 # for a general overview of the issue.
 #
 # ***Important***: keep the location of GIT_DIR in sync with the mountpoint of the repository inside the container.
-DOCKER_GIT_ENV = --env GIT_DIR=/data/.git
+DOCKER_GIT_ENV = --env GIT_DIR=/data/.git --env GIT_AUTHOR_NAME="$(shell git config user.name)" --env GIT_AUTHOR_EMAIL="$(shell git config user.email)"
 
 PANDOC        = $(DOCKER_COMMAND) $(DOCKER_VOLUME)     $(DOCKER_USER) --entrypoint="pandoc"                                  $(DOCKER_IMAGE)
 HUGO          = $(DOCKER_COMMAND) $(DOCKER_VOLUME)     $(DOCKER_USER) --entrypoint="hugo"                                    $(DOCKER_IMAGE)