Ensure the source distribution is complete

Several files present in VCS were not included in the distribution
tarball.

Drop the obsolete appveyor configuration.

.github/workflows/tests.yml

@@ -25,12 +25,13 @@ jobs:
         with:
           python-version: 3.8
       - name: Install packages
-        run: pip install mypy ruff types-certifi types-pyopenssl
+        run: pip install check-manifest mypy ruff types-certifi types-pyopenssl
       - name: Run linters
         run: |
           ruff .
           ruff format --check --diff .
           mypy src tests
+          check-manifest
 
   codespell:
     name: Check for spelling errors

MANIFEST.in

@@ -1,4 +1,7 @@
+exclude .readthedocs.yaml
 include LICENSE
-recursive-include docs *.py *.rst Makefile
-recursive-include examples *.css *.html *.py *.txt
+recursive-include docs *.py *.rst *.svg Makefile
+recursive-include examples *.css *.html *.py *.rst *.txt
+recursive-include requirements *.txt
+recursive-include scripts *.json *.py
 recursive-include tests *.bin *.pem *.py