New build version scheme (#305)

* Use separate build tag file

* Implement new versioning scheme

* Update workflow file

Former-commit-id: 80bbbafeb6

app/version.py

@@ -23,7 +23,7 @@ def command(ctx):
 
     # See: https://stackoverflow.com/a/20885799/1701505
     from . import data
-    with importlib.resources.open_text(data, "version.txt") as version_file:
+    with importlib.resources.open_text(data, "build_tag.txt") as version_file:
         # TODO: code better version that skips comment lines
         version_string = version_file.read().splitlines()[1]