android build: pin hashes of p4a recipes

contrib/android/p4a_recipes/certifi/__init__.py

@@ -0,0 +1,15 @@
+from pythonforandroid.recipe import PythonRecipe
+
+
+assert PythonRecipe.depends == ['python3']
+assert PythonRecipe.python_depends == []
+
+
+class CertifiRecipePinned(PythonRecipe):
+    version = "2020.12.5"
+    sha512sum = "3425d98f19025e70d885458629071c8531271d93d1461fadea6afbaafc763881a42b3c05be391a938d84a0d1ab729c3ac5df4f3328e8ef63a7b56ead1445bddd"
+    url = "https://pypi.python.org/packages/source/c/certifi/certifi-{version}.tar.gz"
+    depends = ["setuptools"]
+
+
+recipe = CertifiRecipePinned()