sceptre: revision bump for python@3.8

Formula/sceptre.rb

@@ -5,6 +5,7 @@ class Sceptre < Formula
   homepage "https://sceptre.cloudreach.com"
   url "https://github.com/cloudreach/sceptre/archive/v2.2.1.tar.gz"
   sha256 "86a2630d46f37adcd36b692e0788006777d130872d4de84a3e0ff36c29fa4dbe"
+  revision 1
 
   bottle do
     cellar :any_skip_relocation
@@ -13,7 +14,7 @@ class Sceptre < Formula
     sha256 "445841f4807d0d76606a7dcc6fd90d279f9aca66f410e78c8be09ea838f970ae" => :high_sierra
   end
 
-  depends_on "python"
+  depends_on "python@3.8"
 
   resource "boto3" do
     url "https://files.pythonhosted.org/packages/36/d0/271327b50232d2e746b7a17b265be857f2fd086d40653b93415fc32e2a4f/boto3-1.10.39.tar.gz"