Sigh, switch to Pipenv

Currently, despite being clearly way better designed, Pyflow isn't quite
practical because every time you run a Pyflow command, it messes with
its own lockfile? Even if it doesn't try to install anything, it
reorders the file and produces spurious Git diffs. Not good.

I tried Poetry as well, but it's not as big an improvement over Pipenv
as Pyflow would've been, so I'm gonna continue using Pipenv for the time
being. Sigh.

Pipfile

@@ -0,0 +1,15 @@
+[[source]]
+url = "https://pypi.org/simple"
+verify_ssl = true
+name = "pypi"
+
+[packages]
+markovify = "*"
+beautifulsoup4 = "*"
+requests = "*"
+"Mastodon.py" = "*"
+
+[dev-packages]
+
+[requires]
+python_version = "3.9"