Add py.typed file to hopefully make the types accessible to users of …

…the library. See: https://blog.whtsky.me/tech/2021/dont-forget-py.typed-for-your-typed-python-package/

pyproject.toml

@@ -3,7 +3,7 @@
     description="An implementation of transformers tailored for mechanistic interpretability."
     license="MIT"
     name="transformer-lens"
-    packages=[{include="transformer_lens"}]
+    packages=[{include="transformer_lens"}, {include="transformer_lens.py.typed"}]
     readme="README.md"
     # Version is automatically set by the pipeline on release
     version="0.0.0"
@@ -129,10 +129,7 @@
     # All rules apart from base are shown explicitly below
     deprecateTypingAliases=true
     disableBytesTypePromotions=true
-    exclude = [
-        "*/**/*.py",
-        "!/transformer_lens/hook_points.py"
-    ]
+    exclude=["!/transformer_lens/hook_points.py", "*/**/*.py"]
     reportAssertAlwaysTrue=true
     reportConstantRedefinition=true
     reportDeprecated=true
@@ -188,4 +185,3 @@
     strictListInference=true
     strictParameterNoneValue=true
     strictSetInference=true
-