pmb.parse.apkindex: Add missing type hint in package()

Make sure to annotate the 'package' parameter as string.

pmb/parse/apkindex.py

@@ -439,7 +439,7 @@ def provider_shortest(providers: dict[str, ApkindexBlock], pkgname: str) -> Apki
 
 # This can't be cached because the APKINDEX can change during pmbootstrap build!
 def package(
-    package, arch: Arch | None = None, must_exist=True, indexes=None, user_repository=True
+    package: str, arch: Arch | None = None, must_exist=True, indexes=None, user_repository=True
 ) -> ApkindexBlock | None:
     """
     Get a specific package's data from an apkindex.