Removed deprecated make rule.

Makefile

@@ -103,6 +103,3 @@ install: clean ## install the package to the active Python's site-packages
 
 gitlab_CI_docker:  ## Build a docker image for CI use within gitlab
 	cd ./tests/CI_docker/; bash ./build_testsuite_image.sh
-
-conda_pyenv_docker:  ## Build a docker image containing Anaconda environment with all basic dependencies installed
-	cd ./tests/CI_docker/; bash ./build_conda_pyenv.sh