[enh] add pyrightconfig.json

By adding this file Pyright automatically detects the
packages from our Python virtual environment.

This can be tested by using the Pyright extension
for VS Code or by running npx pyright.

pyrightconfig.json

@@ -0,0 +1,4 @@
+{
+    "venvPath": "local",
+    "venv": "py3"
+}