Use conda to create test environment.

Signed-off-by: Daniel Scheffler <danschef@gfz-potsdam.de>

.gitlab-ci.yml

@@ -57,7 +57,7 @@ test_geoarray_install:
     - mamba update -n base -c conda-forge --all
 
     # create geoarray environment from environment_geoarray.yml
-    - mamba env create -v -v --name geoarray_test -f tests/CI_docker/context/environment_geoarray.yml
+    - conda env create -v -v --name geoarray_test -f tests/CI_docker/context/environment_geoarray.yml
     - conda activate geoarray_test
 
     # install geoarray