Fix mypy and black checks

qt/aqt/addons.py

@@ -47,8 +47,8 @@ class AddonInstallationResult(NamedTuple):
 
 class AddonManager:
 
-    ext = ".ankiaddon"
-    _manifest_schema = {
+    ext: str = ".ankiaddon"
+    _manifest_schema: dict = {
         "type": "object",
         "properties": {
             "package": {"type": "string", "meta": False},

qt/aqt/main.py

@@ -1027,6 +1027,7 @@ QTreeWidget {
 
     def installAddon(self, path):
         from aqt.addons import installAddonPackages
+
         installAddonPackages(self.addonManager, [path], external=True, parent=self)
 
     # Cramming

qt/aqt/utils.py

@@ -57,7 +57,7 @@ def showInfo(
     type="info",
     title="Anki",
     textFormat=None,
-    customBtns=None
+    customBtns=None,
 ):
     "Show a small info window with an OK button."
     if parent is False: