dev: Avoid pyright version 1.1.217 in CI

It contains a regression¹ that reports errors about using Protocol from
typing_extensions on Python 3.6.  If you have pyright pre-installed
locally (instead of just-in-time installed via npx), manually downgrade
to pyright 1.1.216 to avoid spurious errors.

¹ microsoft/pyright#2987

tests/pyright.py

@@ -8,7 +8,7 @@
 if which("pyright"):
     pyright = ["pyright"]
 elif which("npx"):
-    pyright = ["npx", "pyright"]
+    pyright = ["npx", "pyright@<1.1.217 || >1.1.217"]
 else:
     pyright = None