Typing: improve kivy type stubs (#2681)

typings/kivy/graphics/texture.pyi

@@ -0,0 +1,13 @@
+""" FillType_* is not a real kivy type - just something to fill unknown typing. """
+
+from typing import Sequence
+
+FillType_Vec = Sequence[int]
+
+
+class FillType_Drawable:
+    def __init__(self, *, pos: FillType_Vec = ..., size: FillType_Vec = ...) -> None: ...
+
+
+class Texture:
+    pass