geos: move to Python 3

Formula/geos.rb

@@ -3,6 +3,7 @@ class Geos < Formula
   homepage "https://trac.osgeo.org/geos"
   url "https://download.osgeo.org/geos/geos-3.7.1.tar.bz2"
   sha256 "0006c7b49eaed016b9c5c6f872417a7d7dc022e069ddd683335793d905a8228c"
+  revision 1
 
   bottle do
     cellar :any
@@ -12,18 +13,19 @@ class Geos < Formula
   end
 
   depends_on "swig" => :build
-  depends_on "python@2"
+  depends_on "python"
 
   def install
     # https://trac.osgeo.org/geos/ticket/771
     inreplace "configure" do |s|
-      s.gsub! /PYTHON_CPPFLAGS=.*/, %Q(PYTHON_CPPFLAGS="#{`python-config --includes`.strip}")
+      s.gsub! /PYTHON_CPPFLAGS=.*/, %Q(PYTHON_CPPFLAGS="#{`python3-config --includes`.strip}")
       s.gsub! /PYTHON_LDFLAGS=.*/, 'PYTHON_LDFLAGS="-Wl,-undefined,dynamic_lookup"'
     end
 
     system "./configure", "--disable-dependency-tracking",
                           "--prefix=#{prefix}",
-                          "--enable-python"
+                          "--enable-python",
+                          "PYTHON=#{Formula["python"].opt_bin}/python3"
     system "make", "install"
   end