Add return value to AdapterContainer.__init__ and AdapterMeta.__new__ (…

…dbt-labs#8523)

.changes/unreleased/Under the Hood-20230830-140231.yaml

@@ -0,0 +1,6 @@
+kind: Under the Hood
+body: Mypy errors - adapters/factory.py
+time: 2023-08-30T14:02:31.519929-04:00
+custom:
+  Author: gshank
+  Issue: "8387"

core/dbt/adapters/base/meta.py

@@ -93,7 +93,7 @@ class AdapterMeta(abc.ABCMeta):
     _available_: FrozenSet[str]
     _parse_replacements_: Dict[str, Callable]
 
-    def __new__(mcls, name, bases, namespace, **kwargs):
+    def __new__(mcls, name, bases, namespace, **kwargs) -> "AdapterMeta":
         # mypy does not like the `**kwargs`. But `ABCMeta` itself takes
         # `**kwargs` in its argspec here (and passes them to `type.__new__`.
         # I'm not sure there is any benefit to it after poking around a bit,

core/dbt/adapters/factory.py

@@ -19,7 +19,7 @@
 
 
 class AdapterContainer:
-    def __init__(self):
+    def __init__(self) -> None:
         self.lock = threading.Lock()
         self.adapters: Dict[str, Adapter] = {}
         self.plugins: Dict[str, AdapterPlugin] = {}