Use GIT_STRING and not GIT_TAG for version

This makes sure that the conda package for the dev branch
is appended with '_latest'.

Author: dragly

.conda-recipe/meta.yaml

@@ -1,6 +1,6 @@
 package:
   name: exdir
-  version: {{ environ.get("GIT_TAG", "0.0.0_custom")|replace("v", "")|replace("-", "_") }}
+  version: {{ environ.get("GIT_STRING", "0.0.0_custom")|replace("v", "")|replace("-", "_") }}
 
 source:
   git_url: ..