[ty] Add None completion task to evaluation

Since `None` is a keyword, it isn't currently included in completions.
But this is a common papercut that is really annoying, and actually
makes typing `None` into the playground nearly impossible. So let's try
to fix this.

Author: BurntSushi

crates/ty_completion_eval/completion-evaluation-tasks.csv

@@ -5,6 +5,7 @@ higher-level-symbols-preferred,main.py,1,1
 import-deprioritizes-dunder,main.py,0,1
 import-deprioritizes-sunder,main.py,0,1
 internal-typeshed-hidden,main.py,0,4
+none-completion,main.py,0,
 numpy-array,main.py,0,
 numpy-array,main.py,1,1
 object-attr-instance-methods,main.py,0,1

crates/ty_completion_eval/truth/none-completion/completion.toml

@@ -0,0 +1,2 @@
+[settings]
+auto-import = false

crates/ty_completion_eval/truth/none-completion/main.py

@@ -0,0 +1 @@
+x = Non<CURSOR: None>

crates/ty_completion_eval/truth/none-completion/pyproject.toml

@@ -0,0 +1,5 @@
+[project]
+name = "test"
+version = "0.1.0"
+requires-python = ">=3.13"
+dependencies = []