android build: pin hashes of p4a recipes

contrib/android/p4a_recipes/six/__init__.py

@@ -0,0 +1,13 @@
+from pythonforandroid.recipes.six import SixRecipe
+
+
+assert SixRecipe._version == "1.15.0"
+assert SixRecipe.depends == ['setuptools', 'python3']
+assert SixRecipe.python_depends == []
+
+
+class SixRecipePinned(SixRecipe):
+    sha512sum = "eb840ac17f433f1fc4af56de75cfbfe0b54e6a737bb23c453bf09a4a13d768d153e46064880dc763f4c5cc2785b78ea6d3d3b4a41fed181cb9064837e3f699a9"
+
+
+recipe = SixRecipePinned()