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/website

@@ -9,10 +9,12 @@ import argparse
 from typing import List
 from erynwells_me.scripting import Command
 from erynwells_me.weeknotes import WeeknotesCommand
+from erynwells_me.deployment import DeploymentCommand
 
 
 COMMANDS: List[Command] = [
     WeeknotesCommand(),
+    DeploymentCommand(),
 ]