chore: import upstream snapshot with attribution

.gitignore

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+# This file tells git what files to ignore (e.g., you won't see them as
+# untracked with "git status").  Add anything to it that can be cleared
+# without any worry (e.g., by "git clean -Xdf"), because it can be
+# regenerated.  Lines beginning with # are comments.  You can also ignore
+# files on a per-repository basis by modifying the core.excludesfile
+# configuration option (see "git help config").  If you need to make git
+# track a file that is ignored for some reason, you have to use
+# "git add -f". See "git help gitignore" for more information.
+
+
+# Regular Python bytecode file
+*.pyc
+__pycache__/
+
+# Optimized Python bytecode file
+*.pyo
+
+# Vim's swap files
+*.sw[op]
+
+# Generated files from Jython
+*$py.class
+
+# File generated by setup.py using MANIFEST.in
+MANIFEST
+
+# Generated by ctags (used to improve autocompletion in vim)
+tags
+
+my/
+
+# Files generated by setup.py
+dist/
+build/
+
+# Generated by setuptools_scm
+mpmath/_version.py
+
+# Tox files
+.tox/
+
+# Mac OS X Junk
+.DS_Store
+
+# Backup files
+*~
+
+.cache/
+.coverage
+doc/source/_build/
+
+# Pytest cache
+.pytest_cache/
+
+# Files generated by setupegg.py
+mpmath.egg-info/
+.eggs
+
+# Coverage-related files
+.coverage
+htmlcov/
+
+# Visual Studio files
+.vs/
+
+# PyCharm files
+.idea/
+
+# Ignore files cached by Hypothesis (including examples directory so far)
+.hypothesis/
+
+# per-project directories for virtual environments
+venv/
+.venv/