Add a deployment command group to the website script

This group has one command so far: next-tag. It looks at the git tag list and
figured out the next deployment tag. For the most part tags are named like so:

    deploy-%Y-%m-%d-NN

The middle segments are year-month-day, and the last segment is an incrementing
counter. For the most part this number will be 01. On days when I deploy more than
once, it will increment.

scripts/erynwells_me/scripting/command.py

@@ -20,5 +20,5 @@ class Command:
     def help(self) -> str:
         return ''
 
-    def add_arguments(self, _: argparse.ArgumentParser):
+    def add_arguments(self, parser: argparse.ArgumentParser):
         raise NotImplementedError()