Update the manifest file so that the sdist doesn't include all git-tracked files by default.

Author: Ryan Whitmore

.gitignore

@@ -199,4 +199,4 @@ tags
 
 # End of https://www.gitignore.io/api/vim,emacs,python
 
-.benchmarks/
+.benchmarks/

MANIFEST.in

@@ -5,3 +5,48 @@ global-exclude *.pyo
 global-exclude *.orig
 global-exclude *.rej
 global-exclude *~
+
+# IDE and editor files
+global-exclude .vscode
+global-exclude .idea
+global-exclude *.swp
+global-exclude *.swo
+global-exclude .ropeproject
+
+# Test and coverage files
+global-exclude .coverage
+global-exclude .pytest_cache
+global-exclude .tox
+global-exclude htmlcov
+global-exclude .nox
+
+# Build artifacts
+global-exclude build
+global-exclude dist
+global-exclude *.egg-info
+global-exclude .eggs
+
+# Documentation build files
+global-exclude docs/_build
+global-exclude docs/.doctrees
+
+# Environment and configuration files
+global-exclude .env
+global-exclude .venv
+global-exclude venv
+global-exclude env
+global-exclude .python-version
+
+# Git and version control
+global-exclude .git
+global-exclude .gitignore
+global-exclude .gitattributes
+
+# CI/CD and development workflow files
+global-exclude .github
+global-exclude .pre-commit-config.yaml
+global-exclude tox.ini
+global-exclude .pylintrc
+global-exclude Makefile
+global-exclude requirements.txt
+global-exclude MIGRATION_CHECKLIST.md

unification/__init__.py

@@ -1,4 +1,5 @@
 from importlib.metadata import version
+
 from .core import assoc, reify, unify
 from .more import unifiable
 from .variable import Var, isvar, var, variables, vars