Use pyright-action to run pyright, bump pyright (#5274)

I recently published https://github.com/marketplace/actions/run-pyright, which wraps pyright and uses GHA magic to leave diagnostics on commits / PRs (like https://github.com/jakebailey/pyright-action-test/pull/1/files), plus a faster startup time thanks to GHA tool caching and piggy backing off of the `node` install used in GHA itself (so no `setup-node` needed).

This PR switches to that action and leaves a comment noting that the version number is pinned in two places.

This action is a prototype, but I'm pretty confident in it so far.

tests/pyright_test.py

@@ -5,7 +5,7 @@ import subprocess
 import sys
 from pathlib import Path
 
-_PYRIGHT_VERSION = "1.1.126"
+_PYRIGHT_VERSION = "1.1.136"  # Must match tests.yml.
 _WELL_KNOWN_FILE = Path("tests", "pyright_test.py")